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                     U.S. SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                                     FORM 4

                  STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

    Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934,
       Section 17(a) of the Public Utility Holding Company Act of 1935 or
               Section 30(f) of the Investment Company Act of 1940

[_]  Check box if no longer  subject to Section 16. Form 4 or Form 5 obligations
     may continue. See Instruction 1(b).


________________________________________________________________________________
1.   Name and Address of Reporting Person*

     Barlow                           David                             S.
- --------------------------------------------------------------------------------
   (Last)                           (First)             (Middle)

    c/o Enzon, Inc., 20 Kingsbridge Road
- --------------------------------------------------------------------------------
                                    (Street)

    Piscataway,               New Jersey                 08854
- --------------------------------------------------------------------------------
   (City)                           (State)              (Zip)

________________________________________________________________________________
2.   Issuer Name and Ticker or Trading Symbol

                               Enzon, Inc. (ENZN)

________________________________________________________________________________
3.   IRS Identification Number of Reporting Person, if Entity (Voluntary)


________________________________________________________________________________
4.   Statement for Month/Year

                                   April 2000

________________________________________________________________________________
5.   If Amendment, Date of Original (Month/Year)


________________________________________________________________________________
6.   Relationship of Reporting Person to Issuer
     (Check all applicable)

     [x]  Director                             [_]  10% Owner
     [_]  Officer (give title below)           [_]  Other (specify below)

________________________________________________________________________________
7.   Individual or Joint/Group Filing (Check applicable line)

     [x]  Form filed by one Reporting Person
     [_]  Form filed by more than one Reporting Person
________________________________________________________________________________


================================================================================
           Table I -- Non-Derivative Securities Acquired, Disposed of,
                             or Beneficially Owned
================================================================================
6. 4. 5. Owner- Securities Acquired (A) or Amount of ship 3. Disposed of (D) Securities Form: 7. 2. Transaction (Instr. 3, 4 and 5) Beneficially Direct Nature of Transaction Code ------------------------------- Owned at End (D) or Indirect 1. Date (Instr. 8) (A) of Month Indirect Beneficial Title of Security (Month/ ------------ Amount or Price (Instr. 3 (I) Ownership (Instr. 3) Day/Year) Code V (D) and 4) (Instr.4) (Instr. 4) - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 9/30/99 A V 124 A See footnote 1 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/30/99 A V 70 A See footnote 1 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 03/31/00 A V 81 A See footnote 1 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 04-18-00 P 6,500 A $28.25 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 04-18-00 P 2,500 A $27.875 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 04-18-00 P 500 A $28.00 D - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 04-18-00 P 500 A $28125 10,275 D - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ====================================================================================================================================
1) Securities granted by Enzon, Inc. pursuant to the Independent Directors Stock Plan as compensation for service as a member of the Board of Directors of Enzon, Inc. and qualified under Rule 16b-3(c) Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. (Print or Type Responses) (Over) SEC 1474(7-97) FORM 4 (continued) Table II -- Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities) ================================================================================
10. 9. Owner- Number ship of Form 2. Deriv- of Conver- 5. 7. ative Deriv- 11. sion Number of Title and Amount Secur- ative Nature or Derivative 6. of Underlying 8. ities Secur- of Exer- 4. Securities Date Securities Price Bene- ity: In- cise 3. Trans- Acquired (A) Exercisable and (Instr. 3 and 4) of ficially Direct direct Price Trans- action or Disposed Expiration Date ----------------- Deriv- Owned (D) or Bene- 1. of action Code of(D) (Month/Day/Year) Amount ative at End In- ficial Title of Deriv- Date (Instr. (Instr. 3, ---------------- or Secur- of direct Owner- Derivative ative (Month/ 8) 4 and 5) Date Expira- Number ity Month (I) ship Security Secur- Day/ ------ ------------ Exer- tion of (Instr. (Instr. (Instr. (Instr. (Instr. 3) ity Year) Code V (A) (D) cisable Date Title Shares 5) 4) 4) 4) - ------------------------------------------------------------------------------------------------------------------------------------ Stock Option (1) $43.375 01/02/00 A V 10,000 01/02/01 01/02/10 Common Stock 10,000 10,000 D - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ====================================================================================================================================
Explanation of Responses: (1) Acquired pursuant to the Company's Non-Qualified Stock Option Plan and qualified under Rule 16b-3. /s/ David S. Barlow May 3, 2000 ------------------------------- ----------------------- **Signature of Reporting Person Date * If the form is filed by more than one reporting person, see Instruction 4(b)(v). ** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a). Note: File three copies of this Form, one of which must be manually signed. If space provided is insufficient, see Instruction 6 for procedure. Potential Persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.