FILE NO. 333-58269
                                                   FILED PURSUANT TO RULE 424(b)


                                   PROSPECTUS

                                   ENZON, INC.
                                3,983,000 Shares
                                  Common Stock
                                ($.01 par value)

                            ------------------------

     This prospectus (the  "Prospectus")  relates to the offer and sale of up to
3,983,000  shares (the  "Shares") of common  stock,  $.01 par value (the "Common
Stock"),   of  Enzon,  Inc.  (the  "Company"  or  "Enzon")  by  certain  selling
stockholders  of the  Company  (each a  "Selling  Stockholders").  See  "Selling
Stockholders." The Company will not receive any of the proceeds from the sale of
the Shares.

     The  Selling  Stockholders  may sell the Shares from time to time in one or
more transactions  (which may involve block transactions) in the open market, in
negotiated  transactions,  through the writing of options on the Shares (whether
such options are listed on an options exchange or otherwise) or by a combination
of these methods,  at fixed prices that may be changed,  at market prices at the
time of sale, at prices  related to market prices or at negotiated  prices.  The
Selling  Stockholders may effect these  transactions by selling the Shares to or
through broker-dealers, who may receive compensation in the form of discounts or
commissions  from the Selling  Stockholders or from the purchasers of the Shares
for  whom  the  broker-dealers  may act as  agent  or to whom  they  may sell as
principal,  or both in amounts to be negotiated  immediately  prior to the sale.
The Selling  Stockholders  may also pledge the Shares as  collateral  for margin
accounts or loans and the Shares  could be resold  pursuant to the terms of such
accounts or loans.  The Selling  Stockholders,  such  brokers or dealers and any
other participating brokers or dealers may be deemed to be "underwriters" within
the meaning of the Securities Act of 1933, as amended (the "Securities  Act") in
connection with such sales. See "Plan of Distribution."

     In addition,  any securities  covered by this Prospectus  which qualify for
sale  pursuant  to Rule 144 under the  Securities  Act ("Rule  144") may be sold
under Rule 144 rather than pursuant to this Prospectus.  To the extent required,
the  specific  shares  of  Common  Stock to be sold,  the name of any  successor
Selling  Stockholders,  the public offering price,  the names of any such agent,
dealer or underwriter, and any applicable commission or discount with respect to
any particular offer will be set forth in an accompanying Prospectus Supplement.
See "Selling Stockholders" and "Plan of Distribution."

     Neither the Company nor the Selling Stockholders can presently estimate the
amount of  commissions  or  discounts,  if any, that will be paid by the Selling
Stockholders  on  account of their  sale of the  Shares  from time to time.  The
Company will bear all expenses in connection with the registration of the Shares
herein, which expenses are estimated to be approximately  $184,000.  The Selling
Stockholders  will pay any brokerage  compensation in connection with their sale
of the Shares. See "Use of Proceeds."

     The Company's Common Stock is traded in the over-the-counter  market and is
quoted on The Nasdaq National Market,  under the symbol "ENZN." On July 8, 1998
the last  reported  sale price of the Common  Stock,  as  reported on The Nasdaq
National Market was $6.375 per share.




         AN INVESTMENT IN THE SECURITIES OFFERED HEREBY INVOLVES A HIGH
            DEGREE OF RISK. SEE "RISK FACTORS" COMMENCING ON PAGE 7.

          THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE
           SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES
        COMMISSION, NOR HAS THE SECURITIES AND EXCHANGE COMMISSION OR ANY
        STATE SECURITIES COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY
      OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
                                    OFFENSE.

                  The date of this Prospectus is July 10, 1998








                                TABLE OF CONTENTS

                                                                           Page
                                                                           ----
Available Information ...................................................    2

Incorporation of Certain Documents by Reference .........................    2

Prospectus Summary ......................................................    4

Risk Factors ............................................................    7

Use of Proceeds .........................................................   12

Selling Stockholders ....................................................   12

Plan of Distribution ....................................................   15

Legal Matters ...........................................................   16

Experts .................................................................   16


No  dealer,  salesperson  or  other  person  has  been  authorized  to give  any
information  or to make any  representation  not  contained or  incorporated  by
reference in this Prospectus in connection  with this offering.  Any information
or representation  not contained or incorporated by reference herein must not be
relied on as having been authorized by the Company,  the Selling Stockholders or
their respective agents. This Prospectus does not constitute an offer to sell or
the  solicitation of an offer to buy the securities  offered hereby in any state
to any person to whom it is unlawful to make such offer or solicitation.  Except
where otherwise indicated, this Prospectus speaks as of its date and neither the
delivery  of this  Prospectus  nor any sale  made  hereunder  shall,  under  any
circumstances,  create  an  implication  that  there  has been no  change in the
affairs of the Company since the date hereof or that the  information  contained
herein is correct as of any time subsequent to its date.




                              AVAILABLE INFORMATION

     The Company is subject to the informational  requirements of the Securities
Exchange  Act of 1934,  as  amended  (the  "Exchange  Act"),  and in  accordance
therewith  files  reports,  proxy  statements  and  other  information  with the
Securities  and Exchange  Commission  (the  "Commission").  Such reports,  proxy
statements  and other  information  filed by the  Company can be  inspected  and
copied at the public  reference  facilities  maintained by the Commission at 450
Fifth Street,  N.W.,  Washington,  D.C.  20549,  and at the  following  Regional
Offices of the Commission:  New York Regional Office,  Seven World Trade Center,
Suite 1300, New York, New York 10048; and Chicago Regional Office,  Northwestern
Atrium  Center,  500  West  Madison  Street,   Suite  1400,  Chicago,   Illinois
60661-2511.  Copies of such material can be obtained  from the Public  Reference
Section of the Commission at 450 Fifth Street, N.W.,  Washington,  D.C. 20549 at
prescribed  rates.  The  Commission  also  maintains  a Web site  that  contains
reports, proxy and information regarding the Company at (http://www.sec.gov).

     The  Company's  Common  Stock is listed on the Nasdaq  National  Market and
reports,  proxy and information  statements and other information concerning the
Company can be inspected at the National Association of Securities Dealers, 1735
K Street, N.W., 4th Floor, Washington, D.C. 20006-1506.

     The Company has filed with the Commission a Registration  Statement on Form
S-3 (referred to herein together with all amendments and exhibits thereto as the
"Registration  Statement")  under the Securities Act, with respect to the shares
of Common  Stock  offered  hereby.  This  Prospectus  which  forms a part of the
Registration  Statement,  does not contain all of the  information  set forth or
incorporated  by reference in the  Registration  Statement  and the exhibits and
schedules  thereto,  certain parts of which are omitted in  accordance  with the
rules and regulations of the Commission. For further information with respect to
the Company and the shares of Common Stock offered  hereby,  reference is hereby
made to the Registration  Statement,  including the exhibits thereto.  Copies of
the  Registration  Statement,  including the exhibits,  may be obtained from the
Public Reference  Section of the Commission at the  aforementioned  address upon
payment of the fee  prescribed  by the  Commission.  Copies of each document may
also   be   obtained    through   the    Commission's    internet   address   at
http://www.sec.gov.  The  summaries  contained in this  Prospectus of additional
information  included in the  Registration  Statement or any exhibit thereto are
qualified in their entirety by reference to such information or exhibit.

     The following trademarks and service marks appear in or are incorporated by
reference  into,  this  Prospectus:  ADAGEN(R) and  ONCASPAR(R)  are  registered
trademarks  of the Company;  PEGNOLOGY(R)  is a  registered  service mark of the
Company;  SCA(R) is a registered  trademark  of Enzon Labs Inc., a  wholly-owned
subsidiary  of the Company;  Intron A(R) is a  registered  trademark of Schering
Corporation.

                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     The Company hereby  incorporates  by reference into this Prospectus (i) its
Annual  Report on Form 10-K for the  Fiscal  Year  Ended  June 30,  1997,  which
contains audited  financial  statements for the Company's latest fiscal year for
which a Form 10-K was required to have been filed and  incorporates by reference
certain  portions of the  Company's  definitive  Proxy  Statement for the Annual
Meeting of  Stockholders  held December 2, 1997, (ii) all other reports filed by
the Company  pursuant to Section  13(a) or 15(d) of the  Exchange Act since June
30, 1997,  including but not limited to, the Quarterly  Reports on Form 10-Q for
the Quarters Ended September 30, 1997,  December 31, 1997 and March 31, 1998 and
the Current Report on Form 8-K filed on June 30, 1998 and (iii) the  description
of the Company's Common Stock,  $.01 par value, as contained in its registration
statement on Form 8-A, filed with the Commission on October 29, 1984, as amended
by a Form 8 filed with the Commission on October 15, 1990.

     All documents filed by the Company  pursuant to Sections  13(a),  13(c), 14
and 15(d) of the Exchange  Act,  subsequent  to the date hereof and prior to the
filing  of a  post-effective  amendment  to  the  Registration  Statement  which
indicates that all shares of Common Stock offered hereby have been sold or which
deregisters all shares of Common Stock then remaining unsold, shall be deemed to
be  incorporated  by reference into this Prospectus and to be a part hereof from
the date of filing of such documents.



                                       2



     Any statement  contained herein or in a document  incorporated or deemed to
be incorporated by reference herein shall be deemed to be modified or superseded
for purposes of this Prospectus to the extent that such statement is modified or
superseded by a statement  contained herein or in a subsequently  filed document
which also is or is deemed to be  incorporated  by  reference  herein.  Any such
statement so modified or superseded  shall not be deemed,  except as so modified
or superseded, to constitute a part of this Prospectus.

     The Company will provide,  without  charge,  to each person  (including any
beneficial  owner) to whom this  Prospectus is  delivered,  upon written or oral
request of such person,  a copy of any and all of the information  that has been
incorporated  by reference in this  Prospectus  (not including  exhibits to such
information unless such exhibits are specifically incorporated by reference into
such  information).  Such  requests  should be  directed  to John  Caruso,  Vice
President,  Administration,  General  Counsel and  Secretary,  at the  Company's
principal  executive  offices at 20  Kingsbridge  Road,  Piscataway,  New Jersey
08854, telephone (732) 980-4500.


                                       3



                               PROSPECTUS SUMMARY

The  following  summary  is  qualified  in its  entirety  by the  more  detailed
information  and the  Consolidated  Financial  Statements  and the Notes thereto
appearing elsewhere herein or incorporated by reference in this Prospectus. This
Prospectus and such  documents  contain  various  "forward  looking  statements"
within the meaning of Section 27A of the Securities Act of 1933, as amended (the
"Securities  Act"),  which represent the Company's  intentions,  expectations or
beliefs  concerning  future events,  including,  but not limited to,  statements
regarding  management's  expectations or beliefs concerning future events. These
forward-looking  statements are qualified by important  factors that could cause
actual  results  to  differ   materially  from  those  in  the   forward-looking
statements,  including,  without limitation,  those discussed in "Risk Factors."
See "Risk Factors."

                                   The Company

     Overview

     Enzon  is a  biopharmaceutical  company  that  develops,  manufactures  and
markets  enhanced   therapeutics  for  life-threatening   diseases  through  the
application of its two proprietary technologies: (i) polyethylene glycol ("PEG")
modification and (ii) single-chain  antigen-binding  ("SCA") proteins.  Enzon is
focusing  its  research  activities  primarily  in the area of  oncology  and is
applying its proprietary technologies to compounds of known therapeutic efficacy
in order  to  enhance  the  performance  of  these  compounds.  The  Company  is
commercializing  its proprietary  technologies by developing products internally
and in  cooperation  with  strategic  partners.  To date,  the  Company  and its
partners have  successfully  commercialized  two  products,  ONCASPAR and ADAGEN
(described  below).  The Company  currently has two products  under  development
internally  and has  established  more than 15 strategic  alliances  and license
relationships  for the  development of products using the Company's  proprietary
technologies.  The Company believes that its partners are dedicating substantial
resources to the development of products which incorporate  Enzon's  proprietary
technologies.  These  efforts  include the  development  of  PEG-Intron A, a PEG
modified version of Schering-Plough  Corporation's  ("Schering-Plough") product,
INTRON A  (interferon  alfa 2b), a  genetically-engineered  anticancer-antiviral
drug,  for which  Schering-Plough  is  currently  conducting  Phase III clinical
trials.

     PEG Technology

     The  PEG  process   involves   chemically   attaching   PEG,  a  relatively
non-reactive  and non-toxic  polymer,  to proteins,  chemicals and certain other
pharmaceuticals  for the purpose of enhancing their  therapeutic value (the "PEG
Process").  The  attachment of PEG helps to disguise the compound and reduce the
recognition of the compound by the immune system,  generally  lowering potential
immunogenicity  and  extending  the life of such  compounds  in the  circulatory
system.  The PEG Process also increases the solubility of the modified  compound
which  enhances  the  delivery  of  the  native  compound.   To  date,   Enzon's
commercialized products are PEG modified proteins.  Through enhancements,  Enzon
is seeking to apply its PEG technology to more traditional organic compounds.

     The Company has made significant  improvements to the original PEG Process,
collectively  referred to as Second  Generation PEG Technology,  and has applied
for  and  received  certain  patents  covering  some  improvements.  One  of the
components of the Second  Generation PEG  Technology is new linker  chemistries;
the chemical binding of PEG to unmodified proteins. These new linkers provide an
enhanced  binding of the PEG to the protein  resulting in a more stable compound
with increased  circulation life and may result in more activity of the modified
protein.

     The Company also has developed a Third  Generation PEG  Technology  that is
designed to enable the  technology to be expanded to certain  organic  compounds
and  would  give  such  PEG-modified  compounds  "Pro



                                       4



Drug"  attributes.  This is accomplished by attaching PEG to a compound by means
of a covalent bond that is designed to break down over time,  thereby  releasing
the active ingredient in the proximity of various tissues.

The Company believes that the "Pro  Drug/Transport  Technology" has much broader
usefulness in that it can be applied to a wide range of small molecules, such as
cancer chemotherapy agents, antibiotics, anti-fungals and immunosuppressants, as
well as to proteins and peptides, including enzymes and growth factors, although
there can be no assurance that such application will result in safe,  effective,
or commercially viable pharmaceutical products.

     Marketed PEG Products

     The Company has received marketing approval from the United States Food and
Drug  Administration  ("FDA") for two first generation PEG technology  products:
(i) ONCASPAR,  the PEG formulation of asparaginase,  for the indication of acute
lymphoblastic  leukemia  ("ALL") in patients  who are  hypersensitive  to native
forms of  L-asparaginase  and (ii)  ADAGEN,  the PEG  formulation  of  adenosine
deaminase, the first successful application of enzyme replacement therapy for an
inherited  disease  to treat a rare  form of  Severe  Combined  Immunodeficiency
Disease ("SCID"), commonly known as the "Bubble Boy Disease."

     ADAGEN is marketed by Enzon on a worldwide  basis.  ONCASPAR is marketed in
the U.S. and Canada by Rhone-Poulenc Rorer Pharmaceuticals,  Inc. and certain of
its  affiliated  entities  ("RPR")  and in Europe by Medac GmbH  ("Medac").  The
Company  has also  granted  exclusive  licenses  to RPR to sell  ONCASPAR in the
Pacific Rim and Mexico.  The  Company is entitled to  royalties  on the sales of
ONCASPAR in North  America by RPR,  as well as  manufacturing  revenue  from the
production of ONCASPAR.  The Company's  agreements  with RPR for the Pacific Rim
and with Medac  require the partners to purchase  ONCASPAR from the Company at a
set price which  increases  over the term of the  agreements.  In addition,  the
agreements  provide for minimum purchase  quantities.  The Company  manufactures
both ADAGEN and ONCASPAR in its South Plainfield, New Jersey facility.

     PEG Products under Development

     The Company currently has three products created using its Second and Third
Generation  PEG  Technology  in clinical and  preclinical  trials.  The first is
PEG-Intron  A, a PEG modified  version of  Schering-Plough's  product,  INTRON A
(interferon alfa 2b), a  genetically-engineered  anticancer-antiviral  drug, for
which  Schering-Plough is currently conducting Phase III clinical trials for use
in the  treatment  of  hepatitis  C. The second  product  under  development  is
PEG-hemoglobin,  a  proprietary  bovine  hemoglobin-based  oxygen-carrier  being
developed  for the  radiosensitization  of solid hypoxic  tumors,  for which the
Company is currently  conducting a Phase Ib clinical  trial.  The third  product
under development is PROTHECAN, a PEG-modified version of camptothecin, a potent
topoisomerase-1  inhibitor,  for use in certain  cancers,  which is currently in
preclinical studies.

     PEG-Intron A. PEG-Intron A was developed by the Company in conjunction with
Schering-Plough  to have longer lasting  activity and an enhanced safety profile
compared to the currently  marketed form of INTRON A.  PEG-Intron A is currently
in a large scale Phase III clinical  trial in hepatitis C patients in the United
States and Europe.  Other indications being pursued include chronic  myelogenous
leukemia and solid tumors. It is expected that PEG-Intron A will be administered
once a week,  compared to the current  regimen for unmodified  INTRON A of three
times a week. Moreover,  it is anticipated that PEG-Intron A will provide a more
convenient  dosing schedule with an improved side effect profile and an improved
therapeutic index for hepatitis C patients. Currently, some patients on INTRON A
experience debilitating flu-like symptoms.

     Pursuant to an  agreement  with  Schering-Plough,  the Company will receive
royalties on worldwide sales of PEG-Intron A, receive  milestone  payments,  and
has the option to be the  exclusive  manufacturer  of  PEG-Intron A for the U.S.
market.  Schering-Plough's  sales of INTRON A were approximately $598 million in
1997


                                       5



for all approved indications. The worldwide market for alpha interferon products
is  estimated to be in excess of $1 billion for all  approved  indications.  The
patents  covering  Schering-Plough's  INTRON A will begin to expire in 2001. The
Company's  Second  Generation  PEG  Technology  patents  that cover the modified
product should afford Schering-Plough extended patent life for PEG Intron-A.

SCA Technology

     The  Company  also  has an  extensive  licensing  program  for  its  second
proprietary  technology,  SCA protein  technology.  SCA proteins are genetically
engineered  proteins designed to overcome the problems  hampering the diagnostic
and therapeutic use of conventional  monoclonal antibodies.  Preclinical studies
have shown that certain SCA proteins  target and  penetrate  tumors more readily
than  conventional  monoclonal  antibodies.  In  addition  to these  advantages,
because SCA proteins are developed at the gene level, they are better suited for
targeted  delivery of gene therapy  vectors and  fully-human SCA proteins can be
isolated directly, with no need for costly "humanization" procedures. Also, many
gene therapy  methods require that proteins be produced in an active form inside
cells. SCA proteins can be produced  through  intracellular  expression  (inside
cells) more readily than monoclonal antibodies.

     Currently,  there are nine SCA proteins in Phase I or II clinical trials by
various   corporations  and   institutions.   Two  of  these   corporations  and
institutions  have  existing  licenses  with the  Company  with  respect  to SCA
proteins and others are expected to require similar licenses.  Some of the areas
being  explored are cancer  therapy,  cardiovascular  indications  and AIDS. The
Company has granted  non-exclusive  SCA licenses to more than a dozen companies,
including Bristol-Myers Squibb Company, Baxter Healthcare Corporation, Eli Lilly
& Co.,  Alexion  Pharmaceuticals  Inc.,  and the Gencell  division of RPR. These
licenses  generally  provide  for  upfront  payments,   milestone  payments  and
royalties on sales of FDA approved products.

     The  Company's  principal  executive  office  and  mailing  address  is  20
Kingsbridge  Road,  Piscataway,  New Jersey 08054,  and its telephone  number is
(732) 980-4500.

                                                   The Offering

Securities Offered............     This Prospectus relates to an offering by the
                                   Selling   Stockholders  of  up  to  3,983,000
                                   shares of Common Stock of the Company.

Securities Outstanding(1)          As of May 29, 1998 the Company had 31,331,081
                                   shares of  Common  Stock  outstanding.  After
                                   giving  effect  to  the   completion  of  the
                                   private   offering   described   in  "Selling
                                   Stockholders,"   the   Company   would   have
                                   35,314,081    shares    of    Common    Stock
                                   outstanding.

Use of Proceeds ..............     The Company  will not  receive  any  proceeds
                                   from the sale of the Shares offered herein by
                                   the   Selling   Stockholders.   See  "Use  of
                                   Proceeds."

Risk Factors .................     See  "Risk   Factors"  for  a  discussion  of
                                   certain   risk   factors   that   should   be
                                   considered   by   prospective   investors  in
                                   connection  with an  investment in the shares
                                   of Common Stock offered hereby.
- ----------
(1) Excludes 5,417,422 shares reserved for issuance upon exercise of options and
warrants  outstanding at May 29, 1998, at weighted  average  exercise  prices of
$4.03 and $4.17, respectively.


                                       6



                                  RISK FACTORS

     Information  contained  and  incorporated  by reference in this  Prospectus
contains  "forward-looking  statements"  which can be  identified  by the use of
forward-looking  terminology  such  as  "believes,"  "expects,"  "may,"  "will,"
"should," or "anticipates"  or the negative thereof or other variations  thereon
or comparable  terminology,  or by discussions of strategy.  No assurance can be
given that the future results covered by the forward-looking  statements will be
achieved.  The risk  factors set forth below  constitute  cautionary  statements
identifying  important factors with respect to such forward-looking  statements,
including  certain risks and  uncertainties,  that could cause actual results to
vary  materially  from the  future  results  indicated  in such  forward-looking
statements.  Other  factors could also cause actual  results to vary  materially
from the future results indicated in such forward-looking statements.

     An investment in the Shares offered hereby  involves a high degree of risk.
Prospective  investors should  carefully  consider the following risk factors in
addition to the other  information  set forth and  incorporated  by reference in
this Prospectus before making any decision to invest in the Shares.

Accumulated  Deficit and  Uncertainty of Future  Profitability.  The Company was
originally  incorporated  in 1981. To date,  the Company's  sources of cash have
been the  proceeds  from the sale of its  stock  through  public  offerings  and
private  placements,   sales  of  its  FDA  approved  products,   ADAGEN(R)  and
ONCASPAR(R);  sales of its products for research purposes; contract research and
development fees; technology transfer and license fees; and royalty advances. At
March 31, 1998, the Company had an accumulated  deficit of approximately  $114.5
million.  The  Company  expects to incur  operating  losses for the  foreseeable
future.  To date, ADAGEN and ONCASPAR are the only products of the Company which
have been approved for  marketing in the United  States by the FDA,  having been
approved in March 1990 and February 1994,  respectively.  In addition,  ONCASPAR
has been  approved  for  marketing  in Canada,  Germany and Russia.  In order to
achieve profitable  operations on a continuing basis, the Company,  either alone
or through its  partners,  must  successfully  manufacture,  market and sell its
ADAGEN and ONCASPAR  products and develop,  manufacture and market the Company's
products  which are under  development.  These products are in various stages of
development,  and the period necessary to achieve regulatory approval and market
acceptance of any  individual  product is uncertain and  typically  lengthy,  if
achievable at all.  Potential  investors  should be aware of the  difficulties a
biopharmaceutical enterprise such as the Company encounters,  especially in view
of the intense  competition in the pharmaceutical  industry in which the Company
competes.  There  can be no  assurance  that the  Company's  plans  will  either
materialize or prove  successful,  that its products under  development  will be
successfully developed or that its products will generate revenues sufficient to
enable the Company to achieve profitability.

     Raw Materials and Dependence Upon Suppliers. Except for PEG-hemoglobin, the
Company purchases the unmodified compounds utilized in its approved products and
products under  development  from outside  suppliers.  There can be no assurance
that the purified bovine  hemoglobin  used in the manufacture of  PEG-hemoglobin
can be produced by the  Company in the amounts  necessary  to expand the current
clinical trials. The Company may be required to enter into supply contracts with
outside suppliers for certain unmodified compounds. The Company does not produce
the  unmodified  adenosine  deaminase  used in the  manufacture  of ADAGEN,  the
unmodified forms of  L-asparaginase  used in the manufacture of ONCASPAR and the
unmodified  camptothecin used in the Company's  PROTHECAN product which is under
development and has a supply contract with an outside supplier for the supply of
each of these  unmodified  compounds.  Delays in  obtaining  or an  inability to
obtain  any  unmodified  compound,  including  unmodified  adenosine  deaminase,
unmodified  L-asparaginase,  unmodified bovine blood, or unmodified camptothecin
on reasonable  terms,  or at all,  could have a material  adverse  effect on the
Company's business,  financial condition and results of operations. In the event
the Company is required to obtain an alternate source for an unmodified compound
utilized in a product which is being sold  commercially  or which is in clinical
development, the FDA and relevant foreign regulatory agencies 


                                        7



will likely require the Company to perform additional testing, which would cause
delays and additional  expenses,  to demonstrate that the alternate  material is
biologically  and chemically  equivalent to the unmodified  compound  previously
used. Such evaluations could include chemical, pre-clinical and clinical studies
and could delay  development  of a product  which is in clinical  trials,  limit
commercial  sales  of an  approved  product  and  cause  the  Company  to  incur
significant  additional expenses. If such alternate material is not demonstrated
to be chemically and  biologically  equivalent to the previously used unmodified
compound,  the  Company  will  likely be  required  to repeat some or all of the
pre-clinical and clinical trials  conducted for such compound.  The marketing of
an FDA approved drug could be disrupted while such tests are conducted.  Even if
the alternate material is shown to be chemically and biologically  equivalent to
the previously used compound,  the FDA or relevant foreign regulatory agency may
require the Company to conduct  additional  clinical  trials with such alternate
material.

Patents and Proprietary Technology. The Company has licensed, and been issued, a
number of patents in the United States and other  countries and has other patent
applications pending to protect its proprietary technology. Although the Company
believes that its patents provide certain protection from competition, there can
be no  assurance  that  such  patents  will  be  of  substantial  protection  or
commercial benefit to the Company,  will afford the Company adequate  protection
from competing  products,  will not be challenged or declared  invalid,  or that
additional United States patents or foreign patent equivalents will be issued to
the  Company.  The scope of patent  claims for  biotechnological  inventions  is
uncertain and the Company's patents and patent  applications are subject to this
uncertainty.  The  Company  is  aware  of  certain  issued  patents  and  patent
applications  belonging  to third  parties,  and there may be other  patents and
patent  applications,  containing  subject  matter  which  the  Company  or  its
licensees  or  collaborators  may  require  in order  to  research,  develop  or
commercialize at least some of the Company's products. There can be no assurance
that licenses  under such patents and patent  applications  will be available on
acceptable terms or at all. If the Company does not obtain such licenses,  it or
its partners could  encounter  delays in product market  introductions  while it
attempts  to design  around  such  patents or could  find that the  development,
manufacture or sale of products requiring such licenses could be foreclosed.  If
the Company does obtain such  licenses it will in all  likelihood be required to
make  royalty and other  payments to the  licensors,  thus  reducing the profits
realized by the Company from the products covered by such licenses.  The Company
is aware that certain  organizations  are engaging in  activities  that infringe
certain  of the  Company's  PEG  technology  and SCA  patents.  There  can be no
assurance  that the Company  will be able to enforce its patent and other rights
against such  organizations.  The Company  expects that there may be significant
litigation in the industry  regarding patents and other proprietary  rights and,
if  Enzon  were to  become  involved  in such  litigation,  it could  consume  a
substantial amount of the Company's resources.  In addition,  the Company relies
heavily on its proprietary  technologies  for which pending patent  applications
have been filed and on unpatented know-how developed by the Company.  Insofar as
the Company  relies on trade  secrets and  unpatented  know-how to maintain  its
competitive  technological  position,  there can be no assurance that others may
not independently develop the same or similar technologies. Although the Company
has  taken  steps  to  protect  its  trade  secrets  and  unpatented   know-how,
third-parties  nonetheless may gain access to such information.  The Company has
two research and license  agreements  with The Green Cross  Corporation  ("Green
Cross")  regarding  rHSA. The Company and Yoshitomi  Pharmaceutical  Industries,
Ltd.  ("Yoshitomi"),  the successor to Green Cross'  business,  are currently in
arbitration to resolve the amount of royalties that will be due the Company,  if
any. In April 1998,  Yoshitomi  filed  documents in such  arbitration  seeking a
declaratory  judgment that under its agreement with the Company no royalties are
payable.  Any adverse decision from such an arbitration  proceeding could result
in a  material  adverse  effect  to the  Company's  future  business,  financial
condition and results of operations.  Research  Corporation  Technologies,  Inc.
("Research  Corporation") held the original patent upon which the PEG Process is
based and had  granted  the  Company  a  license  under  such  patent.  Research
Corporation's  patent  for  the  PEG  Process  in  the  United  States  and  its
corresponding  foreign  patents have expired.  Although the Company has obtained
several improvement patents in connection with the PEG Process,  there can be no
assurance  that  any of  these  patents  will  enable  the  Company  to  prevent
infringement or that competitors will not develop  competitive  products outside
the protection  that may be afforded by these patents.  The Company is aware 



                                       8



that others have also filed patent applications and have been granted patents in
the United States and other  countries with respect to the application of PEG to
proteins  and  other  compounds.  Based  upon  the  expiration  of the  Research
Corporation  patent,  other  parties  will be  permitted  to make,  use, or sell
products covered by the claims of the Research  Corporation  patent,  subject to
other patents,  including  those held by the Company.  There can be no assurance
that the expiration of the Research  Corporation patent will not have a material
adverse effect on the business, financial condition and results of operations of
the Company.

Limited Sales and Marketing Experience;  Dependence on Marketing Partners. Other
than ADAGEN,  which the Company  markets on a worldwide basis to a small patient
population,  the Company does not engage in the direct  commercial  marketing of
any of its products and therefore does not have significant  sales and marketing
experience.  For certain of its  products,  the Company has  provided  exclusive
marketing  rights to its  corporate  partners  in  return  for  royalties  to be
received on sales.  With respect to ONCASPAR,  the Company has granted exclusive
marketing  rights in North  America and the Pacific Rim to RPR.  The Company has
also granted  exclusive  marketing rights in Europe and Russia to Medac Gmbh and
in Israel  to Tzamal  Pharma  Ltd..  The  Company  expects  to retain  marketing
partners to market ONCASPAR in other foreign markets, principally South America,
and is currently pursuing arrangements in this regard. There can be no assurance
that such  efforts  will result in the  Company  concluding  such  arrangements.
Regarding the marketing of certain of the Company's other future  products,  the
Company  expects to evaluate  whether to create a sales force to market  certain
products in the United States or to continue to enter into license and marketing
agreements with others for United States and foreign  markets.  These agreements
generally  provide that all or a  significant  portion of the marketing of these
products will be conducted by the Company's licensees or marketing partners.  In
addition,  under  certain  of  these  agreements,  the  Company's  licensees  or
marketing partners may have all or a significant  portion of the development and
regulatory approval responsibilities. There can be no assurance that the Company
will be able to control the amount and timing of resources  that any licensee or
marketing  partner may devote to the Company's  products or prevent any licensee
or marketing  partner from pursuing  alternative  technologies  or products that
could result in the  development  of products  that  compete with the  Company's
products and the  withdrawal of support for the Company's  products.  Should the
licensee  or  marketing  partner  fail to develop a  marketable  product (to the
extent it is responsible  for product  development)  or fail to market a product
successfully,  if it is developed,  the Company's business,  financial condition
and results of operations may be adversely  affected.  There can be no assurance
that the Company's  marketing  strategy will be successful.  Under the Company's
marketing and license agreements, the Company's marketing partners and licensees
may have the right to  terminate  the  agreements  and  abandon  the  applicable
products at any time for any reason without significant payments. The Company is
aware that certain of its marketing  partners are pursuing parallel  development
of products on their own and with other collaborative partners which may compete
with the  licensed  products and there can be no  assurance  that the  Company's
other  current or future  marketing  partners will not also pursue such parallel
courses.

Reimbursement from Third-Party  Payors.  Sales of the Company's products will be
dependent in part on the availability of reimbursement from third-party  payors,
such as governmental health administration authorities,  private health insurers
and  other   organizations.   Government  and  other   third-party   payors  are
increasingly  sensitive to the containment of health care costs and are limiting
both coverage and levels of reimbursement for new therapeutic  products approved
for  marketing,  and are  refusing,  in some cases,  to provide any coverage for
indications for which the FDA and other national health  regulatory  authorities
have not  granted  marketing  approval.  There  can be no  assurance  that  such
third-party payor  reimbursement will be available or will permit the Company to
sell its products at price levels  sufficient  for it to realize an  appropriate
return on its  investment  in product  development.  Since  patients who receive
ADAGEN  will be  required  to do so for  their  entire  lives  (unless a cure or
another treatment is developed),  lifetime limits on benefits which are included
in most  private  health  insurance  policies  could  permit  insurers  to cease
reimbursement for ADAGEN. Lack of or inadequate  reimbursement by government and
other  third  party  payors  for the  Company's  products  would have a material
adverse  effect on the Company's  business,  financial  condition and results of
operations.


                                       9



Government  Regulation.   The  manufacturing  and  marketing  of  pharmaceutical
products in the United  States and abroad is subject to  stringent  governmental
regulation  and the sale of any of the  Company's  products for use in humans in
the United States will require the prior approval of the FDA. Similar  approvals
by  comparable  agencies  are required in most  foreign  countries.  The FDA has
established  mandatory  procedures  and  safety  standards  which  apply  to the
clinical  testing,   manufacture  and  marketing  of  pharmaceutical   products.
Pharmaceutical  manufacturing  facilities are also regulated by state, local and
other authorities. Obtaining FDA approval for a new therapeutic may take several
years and involve  substantial  expenditures.  ADAGEN was approved by the FDA in
March 1990.  ONCASPAR  was approved by the FDA in February  1994,  in Germany in
November  1994 and in  Canada  in 1997 in each  case  for  patients  with  acute
lymphoblastic leukemia who are hypersensitive to native forms of L-asparaginase.
ONCASPAR was approved in Russia for therapeutic use in a broad range of cancers.
Except for these  approvals,  none of the  Company's  other  products  have been
approved for sale and use in humans in the United States or elsewhere. There can
be no assurance  that the Company will be able to obtain FDA approval for any of
its other products. In addition, any approved products are subject to continuing
regulation,  and  noncompliance by the Company with applicable  requirements can
result in  criminal  penalties,  civil  penalties,  fines,  recall  or  seizure,
injunctions  requiring  suspension  of  production,   orders  requiring  ongoing
supervision  by the FDA or refusal by the  government  to approve  marketing  or
export  applications  or to allow the  Company to enter into  supply  contracts.
Failure to obtain or maintain  requisite  governmental  approvals  or failure to
obtain or maintain approvals of the scope requested,  will delay or preclude the
Company or its licensees or marketing partners from marketing their products, or
limit the  commercial  use of the  products,  and  thereby  may have a  material
adverse  affect on the Company's  business,  financial  condition and results of
operations.

Intense  Competition and Risk of  Technological  Obsolescence.  Many established
biotechnology and pharmaceutical  companies with resources greater than those of
the Company are engaged in activities  that are  competitive  with the Company's
and may  develop  products  or  technologies  which  compete  with  those of the
Company.  The Company is aware that other companies are engaged in utilizing PEG
technology  in  developing  drug  products.  There can be no assurance  that the
Company's  competitors  will not  successfully  develop,  manufacture and market
competing  products  utilizing  PEG  technology  or  otherwise.  Other  drugs or
treatment  modalities which are currently  available or that may be developed in
the  future,  and which treat the same  diseases  as those  which the  Company's
products are designed to treat, may be competitive with the Company's  products.
There can be no assurance that the Company will be able to compete  successfully
against current or future  competitors or that such  competition will not have a
material  adverse  effect on the  Company's  business,  financial  condition and
results of operations.  Rapid technological  development by others may result in
the  Company's   products  becoming  obsolete  before  the  Company  recovers  a
significant portion of the research,  development and commercialization expenses
incurred with respect to those products.  The Company's success,  in large part,
depends  upon  developing  and   maintaining  a  competitive   position  in  the
development of products and  technologies in its area of focus.  There can be no
assurance  that  the  Company's  competitors  will  not  succeed  in  developing
technologies  or products that are more  effective than any which are being sold
or developed by the Company or which would render the Company's  technologies or
products  obsolete  or  noncompetitive.  The  Company's  failure to develop  and
maintain a competitive position with respect to its products and/or technologies
would have a material  adverse effect on its business,  financial  condition and
results of operations.

Uncertainty of Market Acceptance.  The Company's products,  ONCASPAR and ADAGEN,
have  been  approved  by the FDA to  treat  patients  with  acute  lymphoblastic
leukemia  and  a  rare  form  of  severe  combined   immunodeficiency   disease,
respectively.  Neither  product has become  widely used due to the small patient
population and limited  indications  approved by the FDA. The Company's  current
research  and   development   efforts  are  directed   towards   developing  new
technologies  to aid in drug  delivery.  Assuming  that the  Company  is able to
develop such  technologies  and secure the requisite FDA  approvals,  the market
acceptance of any such  products will depend upon the  acceptance by the medical
community of the use of such  technologies.  There can be no assurance  that any
additional  products  will be  approved  by the FDA or that,  if  approved,  the
medical


                                       10



community  will use them.  In addition,  the use of any such new  products  will
depend upon the extent of third party medical reimbursement, increased awareness
of the  effectiveness  of such  technologies and sales efforts by the Company or
any marketing  partner.  The Company's  proprietary  PEG technology has received
only limited  market  acceptance to date.  Failure of the Company to develop new
FDA approved  products and to achieve market  acceptance for such products would
have a material adverse effect on the Company's  business,  financial  condition
and results of operation.

Potential Product Liability. The use of the Company's products during testing or
after  regulatory  approval  entails an inherent  risk of adverse  effects which
could  expose the Company to product  liability  claims.  The Company  maintains
product  liability  insurance  coverage  in the total  amount of $10 million for
claims  arising  from the use of its  products in clinical  trials  prior to FDA
approval and for claims arising from the use of its products after FDA approval.
There can be no assurance that the Company will be able to maintain its existing
insurance  coverage or obtain  coverage for the use of its other products in the
future. There can be no assurance that such insurance coverage and the resources
of the Company  would be  sufficient  to satisfy any  liability  resulting  from
product  liability  claims or that a product  liability  claim  would not have a
material  adverse  effect on the  Company's  business,  financial  condition  or
results of operations.

Future Capital Needs; Uncertainty of Additional Financing. The Company's current
sources of liquidity  are its cash  reserves,  and interest  earned on such cash
reserves,  sales of ADAGEN and  ONCASPAR,  sales of its  products  for  research
purposes,  and license fees.  There can be no assurance as to the level of sales
of the Company's FDA approved  products,  ADAGEN and ONCASPAR,  or the amount of
royalties  realized  from  the  commercial  sale  of  ONCASPAR  pursuant  to the
Company's  licensing  agreements.  Total  cash  reserves,  including  short term
investments,  as of March 31, 1998, were approximately  $6.6 million,  and after
giving effect to the  approximately  $17,600,000 of net proceeds received by the
Company  from the  private  placement  of the  Shares  offered  herein,  will be
approximately  24,228,000.   Based  upon  its  currently  planned  research  and
development  activities and related costs and its current  sources of liquidity,
the Company anticipates its current cash reserves will be sufficient to meet its
capital and operational  requirements for the foreseeable  future. The Company's
future  needs and the  adequacy  of  available  funds  will  depend on  numerous
factors, including without limitation,  the successful  commercialization of its
products,  progress in its product development  efforts, the magnitude and scope
of such efforts, progress with preclinical studies and clinical trials, progress
with regulatory affairs activities, the cost of filing,  prosecuting,  defending
and enforcing patent claims and other  intellectual  property rights,  competing
technological  and  market  developments,   and  the  development  of  strategic
alliances for the marketing of its products.  There can be no assurance that the
Company will not require additional  financing for its currently planned capital
and  operational  requirements.  In  addition,  the  Company may seek to acquire
additional  technology,  enter into strategic alliances and engage in additional
research and development programs,  which may require additional financing.  The
Company does not have any committed sources of additional  financing,  and there
can be no assurance that additional funding, if necessary,  will be available on
acceptable  terms,  if at all.  To the  extent  the  Company is unable to obtain
financing,  it may be  required  to curtail its  activities  or sell  additional
securities.  There can be no assurance  that any of the  foregoing  fund raising
activities  will  successfully  meet the Company's  anticipated  cash needs.  If
adequate funds are not available,  the Company's  business,  financial condition
and results of operations will be materially and adversely affected.

Dividend  Policy and  Restrictions.  The  Company has paid no  dividends  on its
Common  Stock,  since its  inception  and does not plan to pay  dividends on its
Common  Stock in the  foreseeable  future.  Except as may be utilized to pay the
dividends  payable on the Company's  Series A Cumulative  Convertible  Preferred
Stock (the  "Series A  Preferred  Stock"),  any  earnings  which the Company may
realize will be retained to finance the growth of the Company. In addition,  the
terms of the Series A Preferred Stock restrict the payment of dividends on other
classes and series of stock.


                                       11



Possible  Volatility  of Stock  Price.  Historically,  the  market  price of the
Company's  Common Stock has  fluctuated  over a wide range and it is likely that
the price of the  Common  Stock  will  fluctuate  in the  future.  Announcements
regarding technical innovations,  the development of new products, the status of
corporate collaborations and supply arrangements,  regulatory approvals,  patent
or proprietary  rights or other  developments  by the Company or its competitors
could have a  significant  impact on the market  price of the Common  Stock.  In
addition,  due to one or more of the  foregoing  factors,  in one or more future
quarters, the Company's results of operations may fall below the expectations of
securities  analysts  and  investors.  In that  event,  the market  price of the
Company's Common Stock could be materially and adversely affected.

Shares  Eligible  for  Future  Sale.  As  of  May  29,  1998,  the  Company  had
approximately  31,331,000  shares of Common Stock  outstanding  and after giving
effect to the consummation of the private offering of 3,983,000 shares of Common
Stock described in "Selling Stockholders" which are offered hereby, but assuming
no additional  shares are issued  pursuant to outstanding  options,  warrants or
convertible securities, would have had approximately 35,314,081 shares of Common
Stock  outstanding.  The  3,983,000  shares of Common Stock  offered  hereby are
"restricted  securities,"  as  that  term  is  defined  in Rule  144  under  the
Securities Act, which when sold pursuant to the  Registration  Statement will be
freely  transferrable  without  restrictions  under the Securities Act, assuming
such Shares are held by  non-affiliates  of the Company.  Of the other shares of
Common Stock  outstanding,  approximately  31,274,000 shares will be immediately
available for sale without  restriction  in the public market and  approximately
26,000 shares will be eligible for sale under Rule 144 of the Securities Act. In
addition,  the  approximately  245,000  shares of  Common  Stock  issuable  upon
conversion  of the Series A Preferred  Stock will be  immediately  available for
sale without  restriction in the public market when issued.  Certain  holders of
the Company's  securities are entitled to registration rights with respect to an
aggregate  of  approximately   1,886,000  shares  of  Common  Stock,   including
approximately  1,039,000 shares underlying outstanding warrants. Of such shares,
approximately  989,000 shares are registered  currently on Form S-3 registration
statements.  The  approximately  4,378,000  shares  of Common  Stock  underlying
outstanding  options which are held by employees,  directors and consultants are
registered on Form S-8 registration statements.  Sales of substantial amounts of
such shares in the public  market or the prospect of such sales could  adversely
affect the market price of the Common Stock.

Anti-takeover  Considerations.  The  Company  has the  authority  to issue up to
3,000,000  shares of Preferred Stock of the Company in one or more series and to
fix the powers,  designations,  preferences  and relative rights thereof without
any further vote of  shareholders.  The issuance of such  Preferred  Stock could
dilute the voting powers of holders of Common Stock and could have the effect of
delaying,  deferring or  preventing a change in control of the Company.  Certain
provisions of the Company's  Articles of  Incorporation  and By-laws,  including
those providing for a staggered Board of Directors, as well as Delaware law, may
operate in a manner that could discourage or render more difficult a takeover of
the  Company  or the  removal  of  management  or may limit  the  price  certain
investors may be willing to pay for shares of Common Stock.

                                 USE OF PROCEEDS

     The  Company  will not  receive  any  proceeds  from the sale of the Shares
offered herein by the Selling Stockholders.  Expenses expected to be incurred by
the Company in connection with this offering are estimated to be $184,000.

                              SELLING STOCKHOLDERS

     The Shares covered by this  Prospectus  were acquired from the Company in a
private  offering  pursuant to Common Stock Purchase  Agreements  (the "Purchase
Agreements") for an aggregate  purchase price of $18,919,250  ($4.75 per share).
The  offer  and  sale  by  the  Company  of the  Common  Stock  to  the  Selling
Stockholders  pursuant  to the  Purchase  Agreements  was  made  pursuant  to an
exemption from the registration



                                       12



requirements  of the  Securities  Act  provided  by Section  4(2)  thereof.  The
Purchase  Agreements contain  representations  and warranties as to each Selling
Stockholder's status as an "accredited investor" as such term is defined in Rule
501  promulgated  under the  Securities  Act.  Warburg Dillon Read LLC (formerly
known as SBC Warburg Dillon Read Inc.) ("Dillon Read"), the placement agent, was
paid a fee of $900,000 or approximately 4.75% of the aggregate purchase price in
connection  with  the  sale  of  the  Shares  by  the  Company  to  the  Selling
Stockholders  pursuant to the  Purchase  Agreements.  In  addition,  the Company
agreed to reimburse  Dillon Read for its travel,  legal and other  out-of-pocket
expenses  incurred in  connection  with the sale of the Shares by the Company to
the Selling Stockholders  pursuant to the Purchase Agreements up to a maximum of
$50,000. The Company paid Evolution Capital, a broker/dealer,  a fee of $235,155
or  approximately  1.25% of the aggregate  purchase price in connection with the
sale of the Shares by the  Company to the Selling  Stockholders  pursuant to the
Purchase Agreements.

     Pursuant  to  the  Purchase   Agreements,   each  Selling  Stockholder  has
represented  that he,  she or it  acquired  the  Shares  for its own  account as
principal, for investment purposes only, and not with a present view to, or for,
the resale distribution  thereof, in whole or in part, within the meaning of the
Securities Act or any state securities law. The Company agreed, in such Purchase
Agreements, to use its best efforts to prepare and file a registration statement
for the resale of the Shares no later than 10 days after the  effective  date of
the  Purchase  Agreements  and to bear  all  expenses  in  connection  with  the
offering,  other than selling commissions,  underwriting fees and stock transfer
taxes applicable to the Shares and all fees and disbursements of counsel for any
Selling Stockholder. Accordingly, in order to permit the Selling Stockholders to
sell the Shares  when each deems  appropriate,  the  Company  has filed with the
Commission a Registration  Statement on Form S-3, of which this Prospectus forms
a part,  with respect to the resale of the Shares from time to time as described
herein and has agreed to prepare and file such amendments and supplements to the
Registration  Statement as may be necessary to keep the  Registration  Statement
effective  until all Shares  offered  hereby have been sold pursuant  thereto or
until  such  shares  are no  longer,  by reason of Rule 144 or any other rule of
similar  effect,  required to be registered  for the sale thereof by the Selling
Stockholders.

     Except  as  otherwise  described  in  "Stock  Ownership,"  prior  to  their
acquisition  of the  Shares,  none of the  Selling  Stockholders  had a material
relationship with the Company.

     In connection  with the  registration of the shares of Common Stock offered
hereby, the Company will supply prospectuses to the Selling Stockholders.

Stock Ownership

     The table  below sets forth (i) the number of shares of Common  Stock owned
beneficially by the Selling  Stockholders as of July 1, 1998; (ii) the number of
shares of Common  Stock being  offered by the Selling  Stockholders  pursuant to
this  Prospectus;  (iii)  the  number  of  shares  of  Common  Stock to be owned
beneficially  by the Selling  Stockholders  after  completion  of the  offering,
assuming that all of the Shares offered hereby are sold; and (iv) the percentage
of the  outstanding  shares  of  Common  Stock to be owned  beneficially  by the
Selling Stockholders after completion of the offering,  assuming that all of the
Shares offered hereby are sold.


                                       13



Number of Percentage of Shares to be Outstanding Shares Number of Owned of Common Stock Shares Beneficially to be Owned Beneficially Number of After Beneficially After Owned as of Shares Completion Completion Selling Stockholders July 1, 1998 Offered of Offering(1) of Offering(1) - -------------------- ------------ -------- -------------- ------------------ DCF Life Sciences Fund Ltd. 200,000 200,000 0 0 DCF Partners, L.P. 853,000 853,000 0 0 Oracle Partners, L.P. 589,589 315,789 273,800 * Oracle Institutional Partners, L.P. 135,996 78,496 57,500 * GSAM Oracle Fund, Inc. 306,721 168,721 138,000 * Haussmann Holdings, N.V. 88,226 50,526 37,700 * Oracle Offshore Ltd. 36,046 18,046 18,000 * Warburg Dillon Read, LLC(2) 517,900 500,000 17,900 * Caduceus Capital, L.P. 105,000 105,000 0 0 Caduceus Capital Ltd. 220,000 220,000 0 0 Merlin BioMed L.P. 21,053 21,053 0 0 Deutsche Vermogensbildungsgesell Schaft mbH 294,737 294,737 0 0 The Aries Trust 1,340,868 747,368 593,500 1.9 Aries Domestic Fund, L.P. 547,964 305,264 242,700 * Wayne P. Rothbaum(3) 58,000 30,000 28,000 * Mitchell D. Silber(3) 35,000 15,000 20,000 * New Technologies Fund 90,000 60,000 30,000 *
* Less than 1%. (Notes continued on following page) 14 (1) Based upon 31,332,831 shares of Common Stock outstanding as of July 1, 1998. Assumes all Shares registered hereby are sold and that no other shares of Common Stock owned by the Selling Stockholders as of July 1, 1998 are sold. Since the Selling Stockholders may sell all, some or none of their Shares, no actual determination can be made of the aggregate number of shares that each Selling Stockholder will own upon completion of the offering to which this Prospectus relates. (2) Warburg Dillon Read LLC (formerly known as SBC Warburg Dillon Read Inc.) acted as the placement agent in the private offering of the Shares to the Selling Stockholders and received a fee of $900,000 or approximately 4.75% of the aggregate purchase price and is entitled to reimbursement by the Company of travel, legal and other out-of-pocket expenses up to a maximum of $50,000. (3) Messrs. Rothbaum and Silber are principals with Evolution Capital, a registered broker-dealer which received a fee of $235,155 or approximately 1.25% of the aggregate purchase price in connection with the sale of the Shares to the Selling Stockholders. In February 1998, Evolution Capital was granted options to purchase 50,000 shares of the Company's Common Stock at an exercise price of $5.9375 per share pursuant to a one year advisory and consulting agreement which requires Evolution Capital to provide institutional targeting, dossier reports, institutional surveillance and overall capital markets intelligence to the Company. In June 1996, The Carson Group Inc., an affiliate of Mr. Rothbaum, Mr. Silber and Evolution Capital, received $325,000 in cash and 50,000 five-year warrants to purchase Common Stock at an exercise price of $4.11 per share as a finder's fee in connection with the Company's private placement of Common Stock, preferred stock and warrants in January and March 1996. In addition, The Carson Group Inc. has received approximately $175,000 in consulting fees during the past two years for providing institutional targeting, dossier reports, institutional surveillance and overall capital markets intelligence to the Company. The Company has agreed to bear the expenses (other than broker discounts and commissions, if any, and expenses of counsel and other advisors to certain of the Selling Stockholders) incurred in connection with the registration of the Shares. PLAN OF DISTRIBUTION The Shares may be sold pursuant to this Prospectus by the Selling Stockholders. These sales may occur from time to time in one or more transactions (which may involve block transactions) in the open markets, in negotiated transactions, through the writing of options on the Shares (whether such options are listed on an options exchange or otherwise) or by a combination of such methods of sale, at fixed prices which may be changed, at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. The Selling Stockholders may effect these transactions by selling the Shares to or through broker-dealers, who may receive compensation in the form of discounts or commissions from the Selling Stockholders or from the purchasers of the Shares for whom the broker-dealers may act as agent or to whom they may sell as principal, or both in amounts to be negotiated immediately prior to the sale. The Selling Stockholders may also pledge the Shares as collateral for margin accounts or loans and the Shares could be resold pursuant to the terms of such accounts or loans. There are currently no agreements, arrangements or understandings with respect to the sale of any of the Shares by the Selling Stockholders. The Shares are being registered to permit public secondary trading of the Shares, and the Selling Stockholders may offer the Shares for resale from time to time. In effecting sales, broker-dealers engaged by the Selling Stockholders may arrange for other broker-dealers to participate. Broker-dealers will receive commissions or discounts from the Selling Stockholders in amounts to be negotiated immediately prior to the sale. Neither the Company nor the Selling Stockholders can presently estimate the amount of commissions or discounts, if any, that will be paid by the Selling Stockholders on account of their sale of the Shares from time to time. In order to comply with the securities laws of certain states, if applicable, the Shares will be sold in such jurisdictions only through registered or licensed brokers or dealers. In addition, in certain states the Shares may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with by the Company and the Selling Stockholders. 15 The Selling Stockholders and any broker-dealers who execute sales for the Selling Stockholders may be deemed to be "underwriters" within the meaning of the Securities Act by virtue of the number of shares of Common Stock to be sold or resold by such persons or entities or the manner of sale thereof, or both. If the Selling Stockholders, broker-dealers or other holders were determined to be underwriters, any discounts or commissions received by them or by brokers or dealers acting on their behalf and any profits received by them on the resale of their shares of Common Stock might be deemed underwriting compensation under the Securities Act. The Selling Stockholders have represented to the Company that any purchase or sale of the Common Stock by them will be in compliance with applicable rules and regulations of the Commission. In addition, any securities covered by this Prospectus which qualify for sale pursuant to Rule 144 under the Securities Act may be sold under Rule 144 rather than pursuant to this Prospectus. To the extent required, the specific shares of Common Stock to be sold, the name of any successor Selling Stockholders, the public offering price, the names of any such agent, dealer or underwriter, and any applicable commission or discount with respect to any particular offer will be set forth in an accompanying Prospectus Supplement. See "Selling Stockholders." Under applicable rules and regulations under the Exchange Act, any person engaged in the distribution of the Shares may not simultaneously engage in market making activities with respect to the Common Stock of the Company for a restricted period prior to the commencement of such distribution. In addition and without limiting the foregoing, the Selling Stockholders and any other person participating in a distribution will be subject to applicable provisions of the Exchange Act and the rules and regulations thereunder, including, without limitation, Regulation M, which provisions may limit the timing of purchases and sales of shares of the Company's Common Stock by the Selling Stockholders. The Company has agreed to indemnify the Selling Stockholders against certain liabilities, including liabilities under the Securities Act. The Selling Stockholders have agreed to indemnify the Company against certain liabilities, including liabilities under the Securities Act. There can be no assurance that the Selling Stockholders will sell all or any of the Shares offered hereby. LEGAL MATTERS The legality of the shares of Common Stock offered hereby has been passed on for the Company by Dorsey & Whitney LLP, New York, New York. EXPERTS The consolidated financial statements of Enzon, Inc. and subsidiaries as of June 30, 1997 and 1996 and for each of the years in the three-year period ended June 30, 1997, have been incorporated by reference herein and in the Registration Statement in reliance upon the report of KPMG Peat Marwick LLP, independent certified public accountants, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing. 16