SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                    FORM 8-K

                                 CURRENT REPORT

     Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934

       Date of Report (Date of earliest event reported) December 23, 1999

                                   ENZON, INC.

             (Exact name of registrant as specified in its charter)



          Delaware                          0-12957                 22-237286
(State or other jurisdiction              (Commission             (IRS Employer
      of incorporation)                   File Number)           Identification)



                20 Kingsbridge Road, Piscataway, New Jersey 08854
               (Address of principal executive offices) (Zip Code)



        Registrant's telephone number, including area code (732) 980-4500



(Former name or former address, if changed since last - report)





Item 5.  Other Events

Company  Announces   Submission  by  Schering-Plough  of  U.S.  Application  for
Peg-Intron for the Treatment of Chronic Hepatitis C

     Enzon,   Inc.  (the  "Company")   announced  that  on  December  23,  1999,
Schering-Plough Corporation submitted a Biologics License Application ("BLA") to
the U.S. Food and Drug Administration  seeking marketing approval for PEG-INTRON
(PEG-interferon  alfa-2b)  Powder for  Injection  for the  treatment  of chronic
hepatitis C in patients 18 years of age or older with compensated liver disease.
PEG-INTRON is a modified form of Schering-Plough's INTRON A (interferon alfa-2b,
recombinant)  Injection that was developed using the Company's PEG technology to
have  longer-acting  properties.  The  application  proposes  administration  of
PEG-INTRON Powder subcutaneously once weekly for one year.

     Schering-Plough  previously  reported  that it has  submitted a centralized
Marketing  Authorization  Application  for  PEG-INTRON  to the European  Union's
European  Agency for the  Evaluation  of  Medicinal  Products.  Approval  of the
centralized Marketing  Authorization  Application for PEG-INTRON would result in
unified labeling that would be valid in all 15 EU-Member States.

     Under the Company's licensing agreement with  Schering-Plough,  the Company
is  entitled  to  royalties  on  worldwide  sales of  PEG-INTRON  and  milestone
payments.  The  filing  of the  BLA by  Schering-Plough  triggers  a $1  million
milestone  payment to the Company.  The Company will  receive an  additional  $2
million milestone payment upon approval of PEG-INTRON.

     Schering-Plough  is continuing its development of PEG-INTRON as combination
therapy with REBETOL  (ribavirin,  USP) for hepatitis C, which is currently in a
multi-national Phase III clinical trial. In addition, PEG-INTRON is in Phase III
clinical  trials for two cancer  indications,  malignant  melanoma  and  chronic
myelogenous  leukemia, as well as in early stage trials for various solid tumors
and other forms of leukemia.

     INTRON A is a recombinant  version of naturally occurring alpha interferon,
which has been  shown to exert  both  antiviral  and  immunomodulatory  effects.
Schering-Plough  markets INTRON A, the world's largest-selling alpha interferon,
for 16 major antiviral and anticancer indications worldwide.





     Except for the historical  information herein, the matters discussed herein
include  forward-  looking  statements  that may  involve  a number of risks and
uncertainties.  Actual  results  may vary  significantly  based upon a number of
factors which are described in the Company's Form 10-K, Form 10-Q's and Form 8-K
on file with the SEC,  including  without  limitation,  risks in  obtaining  and
maintaining  regulatory approval for expanded indications,  market acceptance of
and continuing  demand for the Company's  products and the impact of competitive
products and pricing.





                                   SIGNATURES

     Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
Registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
undersigned hereunto duly authorized.


Dated: January 7, 2000


                                                  ENZON, INC.
                                                  ----------------------------
                                                   (Registrant)

                                        By:       /s/ KENNETH J. ZUERBLIS
                                                  ----------------------------

                                                  Kenneth J. Zuerblis
                                                  Vice President, Finance
                                                  and Chief Financial  Officer