Registration No. 333-__________
      As filed with the Securities and Exchange Commission on June 28, 2001
================================================================================

                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

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

                                   ENZON, INC.
             (Exact name of registrant as specified in its charter)

             Delaware                                          22-2372868
   (State or other jurisdiction                             (I.R.S. Employer
 of incorporation or organization)                         Identification No.)

                               20 Kingsbridge Road
                          Piscataway, New Jersey 08854
                          (Address, including zip code,
                  of registrant's principal executive offices)

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

                   Non-Qualified Stock Option Plan, as amended
                                       and
                        Restricted Stock Award Agreement
                    between Enzon, Inc. and Arthur J. Higgins
                            (Full title of the plan)

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

                               Kenneth J. Zuerblis
                             Chief Financial Officer
                                   Enzon, Inc.
                               20 Kingsbridge Road
                          Piscataway, New Jersey 08854
                                 (732) 980-4500
                      (Name, address and telephone number,
              including area code, of agent for service of process)

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

                                    Copy to:
                             Kevin T. Collins, Esq.
                              Dorsey & Whitney LLP
                                 250 Park Avenue
                               New York, NY 10177
                                 (212) 415-9200

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

                         CALCULATION OF REGISTRATION FEE


=================================================================================================================================
                                        Amount to be       Proposed maximum            Proposed maximum             Amount of
Title of securities to be registered     registered    offering price per share    aggregate offering price     registration fee
- ---------------------------------------------------------------------------------------------------------------------------------
                                                                                                         
      Common Stock, $0.01                 1,700,000            $59.10(1)                 $100,470,000               $25,118
      par value per share
- ---------------------------------------------------------------------------------------------------------------------------------
      Common Stock, $0.01
      par value per share                    25,000            $56.83(2)                 $  1,420,750                $   356
- ---------------------------------------------------------------------------------------------------------------------------------
             Total                                                                                                   $25,474
=================================================================================================================================


(1)  Estimated solely for the purpose of calculating the registration fee in
     accordance with Rule 457(h) under the Securities Act of 1933, as amended,
     on the weighted average of (i) 809,480 shares underlying outstanding
     options under the Non-Qualified Stock Option Plan at a weighted exercise
     price of $61.59 per share and (i) 890,520 balance of the shares underlying
     options to be granted under the Non-Qualified Stock Option Plan at an
     average aggregate offering price of $56.83 per share as computed based upon
     the average of the high and low prices of the registrant's Common Stock on
     the Nasdaq National Market on June 27, 2001.

(2)  Estimated solely for the purpose of calculating the registration fee in
     accordance with Rule 457(c) under the Securities Act of 1933, as amended,
     based upon the average of the high and low prices of the registrant's
     Common Stock on the Nasdaq National Market on June 27, 2001.
================================================================================




                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3. Incorporation of Documents by Reference.

     The following documents, which have been filed with the Securities and
Exchange Commission (the "Commission") by Enzon, Inc. (the "Company"), are
incorporated by reference in this Registration Statement, as of their respective
dates:

     o    the Company's annual report on Form 10-K and 10-K/A for the fiscal
          year ended June 30, 2000;

     o    the Company's proxy statement dated October 27, 2000, filed in
          connection with its annual meeting of stockholders held on December 5,
          2000;

     o    all other reports filed by the Company pursuant to Section 13(a) or
          15(d) of the Exchange Act since June 30, 2000, including but not
          limited to, the Quarterly Reports on Form 10-Q for the quarters ended
          September 30, 2000, December 31, 2000 and March 31, 2001 and the
          Current Reports on Form 8-K filed on August 17, 2000, September 18,
          2000, November 2, 2000, November 6, 2000, November 7, 2000, November
          8, 2000, December 19, 2000, December 21, 2000, January 22, 2001,
          February 6, 2001, February 16, 2001, February 22, 2001, March 26,
          2001, March 30, 2001, May 7, 2001, May 9, 2001, May 23, 2001, June 13,
          2001, June 14, 2001 and June 21, 2001; and

     o    the Company's Form 8-A, filed on October 29, 1984, as amended by Form
          8-A/A filed on October 15, 1990, with respect to its common stock.

     All documents filed by the Company pursuant to Sections 13(a), 13(c), 14
and 15(d) of the Securities Exchange Act of 1934 subsequent to the date hereof
and prior to the filing of a post-effective amendment which indicates that all
securities offered hereby have been sold or which deregisters all securities
remaining unsold shall be deemed to be incorporated by reference herein and to
be a part hereof from the respective dates of filing of such documents.

Item 4. Description of Securities.

     Not applicable.

Item 5. Interests of Named Experts and Counsel.

     Not applicable.

Item 6. Indemnification of Directors and Officers.

     Section 145 of the Delaware General Corporation Law (the "DGCL") empowers a
corporation to indemnify any person who was or is a party or is threatened to be
made a party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative (other than an action
by or in the right of the corporation) by reason of the fact that he or she is
or was a director, officer, employee or agent of the corporation or is or was
serving at the request of the corporation as a director, officer, employee or
agent of another corporation or other enterprise, against expenses (including
attorneys' fees), judgments, fines and amounts paid in settlement actually and
reasonably incurred by him or her in connection with such action, suit or
proceeding if he or she acted in good faith and in a manner



he or she reasonably believed to be in, or not opposed to, the best interests of
the corporation, and, with respect to any criminal action or proceeding, had no
reasonable cause to believe his or her conduct was unlawful.

     Section 145 also empowers a corporation to indemnify any person who was or
is a party or is threatened to be made a party to any threatened, pending or
completed action or suit by or in the right of the corporation to procure a
judgment in its favor by reason of the fact that such person acted in any of the
capacities set forth above, against expenses (including attorneys' fees)
actually and reasonably incurred by him or her in connection with the defense or
settlement of such action or suit if he or she acted under similar standards,
except that no indemnification may be made in respect of any claim, issue or
matter as to which such person shall have been adjudged to be liable to the
corporation unless, and only to the extent that, the Delaware Court of Chancery
or the court in which such action was brought shall determine that despite the
adjudication of liability such person is fairly and reasonably entitled to
indemnity, for such expenses which the Delaware Court of Chancery or such other
court shall deem proper.

     Section 145 further provides that to the extent a director, officer,
employee or agent of a corporation has been successful in the defense of any
action, suit or proceeding referred to above or in the defense of any claim,
issue or matter therein, he or she shall be indemnified against expenses
(including attorneys' fees) actually and reasonably incurred by him or her in
connection therewith, that indemnification provided for by Section 145 shall not
be deemed exclusive of any other rights to which the indemnified party may be
entitled; and that the corporation is empowered to purchase and maintain
insurance on behalf of any person who is or was a director, officer, employee or
agent of the corporation against any liability asserted against him or her in
any such capacity or arising out of his or her status as such, whether or not
the corporation would have the power to indemnify him or her against such
liability under Section 145.

     Article 8 of the Company's by-laws specifies that the registrant shall
indemnify its directors and officers to the full extent permitted by the DGCL.
This provision of the by-laws is deemed to be a contract between the registrant
and each director and officer who serves in such capacity at any time while such
provision and the relevant provisions of the DGCL are in effect, and any repeal
or modification thereof shall not offset any rights or obligations then existing
with respect to any state of facts then or theretofore existing or any action,
suit or proceeding theretofore or thereafter brought or threatened in whole or
in part upon any such state of facts.

     Section 102(b)(7) of the DGCL enables a corporation in its certificate of
incorporation to limit the personal liability of members of its board of
directors for violation of a director's fiduciary duty of care. This Section
does not, however, limit the liability of a director for breaching his duty of
loyalty, failing to act in good faith, engaging in intentional misconduct or
knowingly violating a law, or from any transaction in which the director derived
an improper personal benefit. This Section also will have no effect on claims
arising under the federal securities laws. The Company's certificate of
incorporation limits the liability of its directors as authorized by Section
102(b)(7).

     The Company's officers and directors have executed indemnity agreements
with Enzon which supplement the protections provided by the Company's
certificate of incorporation and by-laws.

     The indemnity agreements provide for indemnification of directors,
officers, employees or agents for liabilities arising out of claims against such
persons acting as directors, officers, employees or agents of the registrant (or
any entity controlling, controlled by or under common control with the
registrant) due to any actual or alleged breach of duty, neglect, error,
misstatement, misleading statement, omission or other act done, or suffered or
wrongfully attempted by such directors, officers, employees and agents, except
as prohibited by law. The indemnity agreements also provide for the advancement
of costs and


                                      II-2


expenses, including attorneys' fees, incurred by directors, officers, employees
and agents in defending or investigating any action, suit, proceeding or claim,
subject to an undertaking by the indemnified person to repay such amounts if it
is ultimately determined that such person is not entitled to indemnification
under such agreement. The indemnity agreements cover future acts and omissions
of directors, officers, employees and agents for which actions may be brought.
The registrant has been advised by its counsel that the indemnity agreements may
also cover acts and omissions of directors, officers, employees and agents which
occurred prior to the execution of the indemnity agreements for which actions
may be brought, although there can be no assurance that, if challenged, such
retroactive indemnification will be upheld under Delaware law. Thus, any
recovery for past acts may be illegal and unenforceable. The foregoing
provisions of the indemnity agreements are consistent with Article 8 of the
registrant's by-laws and the registrant's policy to indemnify directors and
officers to the fullest extent permitted by law.

     The indemnity agreements also provide that directors, officers, employees
and agents are entitled to indemnification against all expenses (including
attorneys' fees) incurred in seeking to collect an indemnity claim or to obtain
advancement of expenses from the registrant.

     The rights of directors, officers, employees and agents under the indemnity
agreements are not exclusive of any other rights directors, officers, employees
and agents may have under Delaware law, any liability insurance policies that
may be obtained, the registrant's by-laws or otherwise. The registrant currently
carries liability insurance for the benefit of its directors and officers which
provides coverage for many of the same matters covered by the indemnity
agreements. The indemnity agreements will not provide indemnification to the
extent that any claims are paid by insurance or through any source of
indemnification other than the indemnity agreements. Moreover, the registrant
would not be required to indemnify a director, officer, employee or agent for
any claim based upon the director, officer, employee or agent gaining, in fact,
a personal profit or advantage to which he or she was not legally entitled, any
claim for accounting of profits made in connection with a violation of Section
16(b) of the Securities Exchange Act of 1934 or a similar state or common law
provision or any claim brought about or contributed to by the dishonesty of the
director, officer, employee and agent. The registrant would be required to
indemnify a director, officer, employee and agent against a claim alleging
improper personal profit or advantage, or dishonesty, unless a final judgment of
a court of competent jurisdiction establishes that such person gained in fact an
improper personal profit or advantage or committed acts of active and deliberate
dishonesty with an actual dishonest purpose and intent and such acts were
material to the adjudicated proceedings. The indemnity agreements provide that
if the registrant pays a director, officer, employee or agent pursuant to such
Agreement, the registrant will be subrogated to the indemnified person's right
to recover from third parties.

Item 7. Exemption from Registration Claimed.

     Not applicable.

Item 8. Exhibits.

     Exhibit    Description
     Number
     ------

      3.1       Certificate of Incorporation, as amended*

      3.2       By-laws, as amended**

      3.3       Amendment to Certificate of Incorporation dated January 5,
                1998***

      4.1       Employment Agreement between Enzon, Inc. and Arthur J.
                Higgins****


                                      II-3


     Exhibit    Description
     Number
     ------

      4.2       Amendment dated May 23, 2001 to Employment Agreement between
                Enzon, Inc. and Arthur J. Higgins dated May 9, 2001****

      4.3       Form of Restricted Stock Award Agreement between Enzon, Inc. and
                Arthur J. Higgins.

      5.1       Opinion of Dorsey & Whitney LLP.

      23.1      Consent of KPMG LLP.

      23.2      Consent of Dorsey & Whitney LLP (contained in Exhibit 5.1 to
                this Registration Statement).

      24.1      Power of Attorney (included on signature page).

      *         Previously filed as an exhibit to the Company's Quarterly Report
                on Form 10-Q for the quarter ended March 31, 1996 and
                incorporated herein by reference.
      **        Previously filed as an exhibit to the Company's Registration
                Statement on Form S-2 (File No. 33-34874) and incorporated
                herein by reference.
      ***       Previously filed as an exhibit to the Company's Quarterly Report
                in Form 10-Q for the quarter ended December 31, 1997 and
                incorporated herein by reference thereto.
      ****      Previously filed as an exhibit to the Company's Current Report
                on Form 8-K dated June 13, 2001.

Item 9. Undertakings.

     (a) The undersigned registrant hereby undertakes:

          (1) To file, during any period in which offers or sales are being
     made, a post-effective amendment to this Registration Statement:

               (i) To include any prospectus required by Section 10(a)(3) of the
          Securities Act of 1933 (the "Securities Act");

               (ii) To reflect in the prospectus any facts or events arising
          after the effective date of the Registration Statement (or the most
          recent post-effective amendment thereof) which, individually or in the
          aggregate, represent a fundamental change in the information set forth
          in the Registration Statement. Notwithstanding the foregoing, any
          increase or decrease in volume of securities offered (if the total
          dollar value of securities offered would not exceed that which was
          registered) and any deviation from the low or high end of the
          estimated maximum offering range may be reflected in the form of
          prospectus filed with the Commission pursuant to Rule 424(b) if, in
          the aggregate, the changes in volume and price represent no more than
          a 20% change in the maximum aggregate offering price set forth in the
          "Calculation of Registration Fee" table in the effective Registration
          Statement; and

               (iii) To include any material information with respect to the
          plan of distribution not previously disclosed in the Registration
          Statement or any material change to such information in the
          Registration Statement;

     Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) above do not
     apply if the information required to be included in a post-effective
     amendment by those paragraphs is contained in periodic reports filed with
     or furnished to the Commission by the registrant pursuant to Section 13 or


                                      II-4


     Section 15(d) of the Exchange Act that are incorporated by reference in the
     Registration Statement.

          (2) That, for the purpose of determining any liability under the
     Securities Act, each such post-effective amendment shall be deemed to be a
     new Registration Statement relating to the securities offered therein, and
     the offering of such securities at that time shall be deemed to be the
     initial bona fide offering thereof.

          (3) To remove from registration by means of a post-effective amendment
     any of the securities being registered which remain unsold at the
     termination of the offering.

     (b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act that is incorporated by reference in the Registration Statement
shall be deemed to be a new Registration Statement relating to the securities
offered therein, and the offering of such securities at that time shall be
deemed to be the initial bona fide offering thereof.

     (c) Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
registrant pursuant to the foregoing provisions, or otherwise, the registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the registrant of expenses incurred or
paid by a director, officer or other controlling person of the registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.


                                      II-5


                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized in the City of Piscataway, State of New Jersey, on June 28, 2001.

                                      ENZON, INC.

                                      By        /s/ ARTHUR J. HIGGINS
                                        ----------------------------------------
                                                      Arthur J. Higgins
                                              President, Chief Executive Officer
                                                        and Director

     KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature
appears below hereby constitutes and appoints Arthur J. Higgins and Kenneth J.
Zuerblis, and each of them, his or her true and lawful attorney-in-fact and
agent, with full powers of substitution and resubstitution, for him or her and
in his or her name, place and stead, in any and all capacities, to sign a
Registration Statement on Form S-8, and any and all amendments (including
post-effective amendments) thereto, and to file the same, with all exhibits
thereto, and other documents in connection therewith, with the Securities and
Exchange Commission, granting unto each such attorney-in-fact and agent full
power and authority to do and perform each and every act and thing requisite or
necessary to be done in and about the premises, as fully to all intents and
purposes as he or she might or could do in person, hereby ratifying and
confirming all that each such attorney-in-fact and agent, or his or her
substitutes, may lawfully do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on June 28, 2001.

       /s/ ARTHUR J. HIGGINS              President, Chief Executive Officer and
- ------------------------------------      Director
        Arthur J. Higgins                 (principal executive officer)


      /s/ KENNETH J. ZUERBLIS             Vice President, Finance and Chief
- ------------------------------------      Financial Officer
       Kenneth J. Zuerblis                (principal financial and accounting
                                          officer)

     /s/  RANDY H. THURMAN                Chairman of the Board
- ------------------------------------
         Randy H. Thurman

                                          Director
- ------------------------------------
         David S. Barlow


        /s/ ROLF A. CLASSON               Director
- ------------------------------------
         Rolf A. Classon


                                      II-6


                                          Director
- ------------------------------------
       Rosina B. Dixon, M.D.

        /s/ DAVID W. GOLDE                Director
- ------------------------------------
       David W. Golde, M.D.

       /s/  ROBERT LEBUHN                 Director
- ------------------------------------
          Robert LeBuhn


                                      II-7


                                EXHIBIT INDEX TO
                                    FORM S-8

                                   Enzon, Inc.

   Exhibit          Description
   Number           -----------
   -------
   5.1              Opinion of Dorsey & Whitney LLP.

   4.3              Form of Restricted Stock Award Agreement between Enzon, Inc.
                    and Arthur J. Higgins.

   23.1             Consent of KPMG LLP.

                                                                     Exhibit 4.3


                        RESTRICTED STOCK AWARD AGREEMENT

     THIS AGREEMENT, made as of this ____ day of [____________________], 2001,
by and between Enzon, Inc., a Delaware corporation (the "Company"), and Arthur
J. Higgins ("Executive").

     WITNESSETH, THAT:

     WHEREAS, The Company wishes to grant a restricted stock award to Executive;

     NOW, THEREFORE, In consideration of the premises and mutual covenants
herein contained, the parties hereto hereby agree as follows:

     1. Award

     The Company, effective as of the date of this Agreement, hereby grants to
Executive a restricted stock award of 25,000 shares (the "Shares") of common
stock of the Company (the "Common Stock") (against Executive's payment of $250
representing the par value thereof), subject to the terms and conditions set
forth herein and to the terms of the Employment Agreement between the Company
and Executive, dated as of May 9, 2001, as amended as of May 23, 2001 (the
"Employment Agreement"). Capitalized terms used but not defined herein shall
have the meanings ascribed to such terms in the Employment Agreement.

     2. Vesting

     Subject to the terms and conditions of this Agreement and Section 10 of the
Employment Agreement, the Executive's Shares shall vest according to the
following schedule:

             Years of Service by Executive as an
           Employee of the Company Following Grant            Vested Percentage
           ---------------------------------------            -----------------

                              0                                   0%

                              1                                   20%

                              2                                   40%

                              3                                   60%

                              4                                   80%

                              5                                   100%

For purposes of this Section 2, years of service by Executive as an employee of
the Company shall begin to accrue on May 31, 2001. One year of service shall
consist of twelve (12) full calendar months of service. Any temporary absence
from employment in excess of six (6) months shall not be considered as years of
service.







     3. Restriction on Transfer

     Until any group of Shares vests pursuant to Sections 2 or 4 hereof, none of
such Shares may be sold, assigned, transferred, pledged, hypothecated or
otherwise disposed of or encumbered, and no attempt to transfer such Shares,
whether voluntary or involuntary, by operation of law or otherwise, shall vest
the transferee with any interest or right in or with respect to such Shares.

     4. Early Vesting; Forfeiture

     (a) Nonvested Shares may vest on an accelerated basis in accordance with
the provisions of Section 10 of the Employment Agreement

     (b) Nonvested Shares may be forfeited in accordance with the provisions of
Section 10 of the Employment Agreement.

     5. Issuance and Custody of Certificate

     (a) The Company shall cause to be issued one or more stock certificates,
registered in the name of Executive, evidencing the Shares. Each such
certificate shall bear the following legends:

     "The shares of common stock represented by this certificate are subject to
forfeiture, and the transferability of this certificate and the shares of stock
represented hereby are subject to the restrictions, terms and conditions
(including restrictions against transfer) contained in an Employment Agreement
entered into between Enzon, Inc. and the registered owner of such shares dated
May 9, 2001, as amended as of May 23, 2001 and a Restricted Stock Award
Agreement entered into between Enzon, Inc. and the registered owner of such
shares. Copies of the Employment Agreement and Restricted Stock Award Agreement
are on file in the office of Enzon, Inc."

     (b) Executive shall cause stock powers relating to the Shares executed by
Executive to be delivered to the Company.

     (c) Each certificate issued pursuant to Section 5(a) hereof, together with
the stock powers relating to the Shares, shall be deposited by the Company with
the Secretary of the Company or a custodian designated by the Secretary. The
Secretary or such custodian shall issue a receipt to Executive evidencing the
certificate or certificates held which are registered in the name of Executive.

     (d) After any Shares subject to this Agreement vest pursuant to Sections 2
or 4(b) hereof, the Company shall promptly cause a certificate or certificates
evidencing such vested Shares, (together with the stock powers relating to the
Shares) to be released and delivered to Executive or Executive's legal
representatives, beneficiaries or heirs.

     (e) Prior to issuance of the Shares, the Company shall have caused such
issuance to be registered under the Securities Act of 1933, as amended.

     6. Distributions and Adjustments



                                       2


     (a) If all or any portion of the Shares vest in Executive subsequent to any
change in the number or character of the shares of Common Stock (through merger,
consolidation, reorganization, recapitalization, stock dividend or otherwise),
Executive shall then receive upon such vesting the number and type of securities
or other consideration which Participant would have received if the Shares had
vested prior to the event changing the number or character of outstanding shares
of Common Stock.

     (b) Any additional shares of Common Stock, any other securities of the
Company and any other property (except for cash dividends) distributed with
respect to the Shares prior to the date the Shares vest shall be subject to the
same restrictions, terms and conditions as the Shares. Any cash dividends
payable with respect to the Shares shall be distributed to Executive at the same
time cash dividends are distributed to shareholders of the Company generally.

     (c) Any additional shares of Common Stock, any securities and any other
property (except for cash dividends) distributed with respect to the Shares
prior to the date such Shares vest shall be promptly deposited with the
Secretary or the custodian designated by the Secretary to be held in custody in
accordance with Section 5(c) hereof.

     7. Taxes

     (a) The issuance of the Shares to Executive pursuant to this Agreement
involves complex and substantial tax considerations, including, without
limitation, consideration of the advisability of Executive making an election
under Section 83(b) of the Internal Revenue Code. The Executive is urged to
consult his own tax advisor with respect to the transactions described in this
Agreement. The Company makes no warranties or representations whatsoever to the
Executive regarding the tax consequences of the grant to the Executive of the
Shares or this Agreement. Executive acknowledges that the making of any Section
83(b) election shall be his personal responsibility.

     (b) In order to provide the Company with the opportunity to claim the
benefit of any income tax deduction which may be available to it in connection
with this restricted stock award, and in order to comply with all applicable
federal or state tax laws or regulations, the Company may take such action as it
deems appropriate to insure that, if necessary, all applicable federal or state
income and social security taxes, which are the sole and absolute responsibility
of Executive, are withheld or collected from Executive.

     (c) Executive may elect to satisfy his federal and state income tax
withholding obligations arising from the receipt of, or the lapse of
restrictions relating to, the Shares by (i) delivering cash, check (bank check,
certified check or personal check) or money order payable to the order of the
Company, (ii) having the Company withhold a portion of the Shares otherwise to
be delivered having a fair market value based on the last reported sale price of
a share of Common Stock on the Nasdaq Stock Market (or if the shares no longer
trade on the Nasdaq Stock Market, the closing or last reported price on the
principal exchange or system on which they trade) (the "Fair Market Value")
equal to the amount of such taxes, or (iii) delivering to the Company Common
Stock having a Fair Market Value equal to the amount of such taxes. The Company
will not deliver any fractional Share but will pay, in lieu thereof, the Fair
Market


                                       3


Value of such fractional Share. The Participant's election must be made on or
before the date that the amount of tax to be withheld is determined. Otherwise,
the Company shall be entitled to withhold taxes due in such manner as the
Company determines in its discretion.

     8. Miscellaneous

     (a) This Agreement is issued pursuant to the Employment Agreement entered
into between the Executive and the Company and is subject to its terms.
Executive hereby acknowledges receipt of a copy of the Employment Agreement. The
Employment Agreement is also available for inspection during business hours at
the principal office of the Company.

     (b) This Agreement shall not confer on Executive any right with respect to
continuance of employment by the Company.

     IN WITNESS WHEREOF, The parties hereto have caused this Agreement to be
executed on the day and year first above written.



                                                 ENZON, INC.



                                                 By:________________________

                                                 Its:________________________



                                                 ____________________________
                                                 Arthur J. Higgins




                                       4

                                                                     Exhibit 5.1

                        [Dorsey & Whitney LLP Letterhead]


                                  June 28, 2001

Enzon, Inc.
20 Kingsbridge Road
Piscataway, NJ  08854

                  Re:   Registration Statement on Form S-8

     Ladies and Gentlemen: You have requested our opinion with respect to the
registration by Enzon, Inc., a Delaware corporation (the "Company"), pursuant to
a Registration Statement on Form S-8 (the "Registration Statement") under the
Securities Act of 1933, as amended, of (i) an aggregate of 1,700,000 shares of
the Company's common stock, $0.01 par value per share (the "Option Shares"),
which are issuable upon the exercise of options (the "Options") to purchase
shares of Common Stock which may have been granted and which may be granted to
employees, officers, directors and consultants of the Company pursuant to the
Company's Non-Qualified Stock Option Plan, as amended (the "Plan"), and (ii)
25,000 shares of the Company's common stock, $0.01 par value per share, which
are issuable pursuant to a Restricted Stock Award Agreement between the Company
and Arthur J. Higgins (the "Restricted Shares").

     In so acting, we have examined original or copies, certified or otherwise
identified to our satisfaction, of such documents, corporate records,
certificates of public officials and other instruments and have conducted such
other investigations of fact and law as we have deemed relevant and necessary to
form a basis for the opinions hereinafter expressed. In conducting such
examination, we have assumed (i) that all signatures are genuine, (ii) that all
documents and instruments submitted to us as copies conform with the originals
and (iii) the due execution and delivery of all documents where due execution
and delivery are a prerequisite to the effectiveness thereof. As to any facts
material to this opinion, we have relied upon statements and representations of
officers and other representatives of the Company and certificates of public
officials and have not independently verified such facts.

     Members of our firm are admitted to the Bar of the State of New York and we
do not express any opinion as to the laws of any jurisdiction other than the
Delaware General Corporation Law.

     Based upon the foregoing, it is our opinion that (i) the Option Shares
issuable upon exercise of the Options issued or issuable under the Plan will be
validly issued, fully paid and non-assessable when issued in accordance with the
Plan and (ii) the Restricted Shares issuable pursuant to the Restricted Stock
Award Agreement will be validly issued, fully paid and non-assessable when
issued in accordance with the Restricted Stock Award Agreement.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.

                                                     Very truly yours,


                                                     DORSEY & WHITNEY LLP

                                                                    EXHIBIT 23.1


                              Accountants' Consent



The Board of Directors
Enzon, Inc.

     We consent to the use of our report incorporated herein by reference.


                                                   /s/  KPMG LLP

Short Hills, New Jersey
June 28, 2001