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                UNITED STATES 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 this box if no longer subject to Section 16. Form 4 or Form 5
     obligations may continue. See Instruction 1(b).

(Print or Type Repsonses)
________________________________________________________________________________
1.   Name and Address of Reporting Person*

   Tombros                          Peter
- --------------------------------------------------------------------------------
   (Last)                           (First)             (Middle)


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

   Piscataway,                      NJ                   08854
- --------------------------------------------------------------------------------
   (City)                           (State)              (Zip)

________________________________________________________________________________
2.   Issuer Name and Ticker or Trading Symbol

     Enzon, Inc. (ENZN)
________________________________________________________________________________
3.   IRS Identification Number of Reporting Person, if an entity (Voluntary)


________________________________________________________________________________
4.   Statement for Month/Year

     December 2000
________________________________________________________________________________
5.   If Amendment, Date of Original (Month/Year)


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

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

         President and Chief Executive Officer
________________________________________________________________________________
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. Transaction (Instr. 3, 4 and 5) Beneficially Direct Nature of 2. Code ------------------------------- Owned at End (D) or Indirect 1. Transaction (Instr. 8) (A) of Month Indirect Beneficial Title of Security Date ------------ Amount or Price (Instr. 3 (I) Ownership (Instr. 3) (mm/dd/yy) Code V (D) and 4) (Instr.4) (Instr. 4) - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/8/00 M 20,000 A $2.6875 - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/8/00 S 20,000 D $68.0000 - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/11/00 M 5,000 A $2.6875 - ------------------------------------------------------------------------------------------------------------------------------------ Common Stock 12/11/00 S 5,000 D $73.0000 30,300 D - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ====================================================================================================================================
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. *If the form is filed by more than one reporting person, see Instruction 4(b)(v). 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. (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 (a) Common (right to buy) $2.6875 12/8/00 M 20,000 9/30/97 9/29/02 Stock 20,000 -- -- - ------------------------------------------------------------------------------------------------------------------------------------ Stock Option (a) Common (right to buy) $2.6875 12/11/00 M 3,000 9/30/97 9/29/02 Stock 3,000 -- -- - ------------------------------------------------------------------------------------------------------------------------------------ Stock Option (a) Common (right to buy) $2.6875 12/11/00 M 2,000 10/30/97 10/29/02 Stock 2,000 -- 98,000 D - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ - ------------------------------------------------------------------------------------------------------------------------------------ ====================================================================================================================================
Explanation of Responses: (a) Granted under the Company's Non-qualified Stock Option Plan and qualified under Rule 16b-3. /s/ Peter Tombros 1/5/01 ------------------------------- ---------------------- **Signature of Reporting Person Date ** 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 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 Number. Page 2 SEC 1474 (7-97)