Exhibit 99.1

                                  NEWS RELEASE
          ENZON ANNOUNCES SCHERING-PLOUGH'S PEGINTRON(TM) RECOMMENDED
        FOR APPROVAL FOR TREATMENT OF HEPATITIS C IN EUROPEAN UNION (EU)

     PISCATAWAY, NJ - February 22, 2000 -- Enzon, Inc. (NASDAQ: ENZN) announced
today that Schering-Plough Corporation (NYSE: SGP) has stated that the Committee
for Proprietary Medicinal Products (CPMP) of the European Agency for the
Evaluation of Medicinal Products (EMEA) has issued a positive opinion
recommending approval of PEGINTRON(TM) (peginterferon alfa- 2b) for the
treatment of adult patients with chronic hepatitis C. PEG-INTRON is a modified
form of Schering's INTRON(R) A (interferon alfa-2b, recombinant) that was
developed using Enzon's PEG technology to have longer-acting properties.

     The Marketing Authorization Application of PEGINTRON is based on clinical
trials in which patients were administered PEGINTRON subcutaneously once weekly
for one year.

     PEGINTRON is indicated in monotherapy in case of intolerance or
contraindication to ribavirin, for the treatment of adult patients with
histologically proven chronic hepatitis C who have serum markers for virus C
replication, e.g. those who have elevated transaminases(1) without liver
decompensation and who are positive for serum HCV-RNA(2) or anti-HCV(3).

     The CPMP opinion serves as the basis for a European Commission approval,
which is typically issued in approximately three months. Commission approval of
the centralized Marketing Authorization Application for PEGINTRON will result in
one single Marketing Authorization with unified labeling that will be valid in
all 15 European Union-Member States.

     Chronic hepatitis C is estimated to affect some 10 million people in major
world markets. As many as 5 million Europeans (1 to 2 percent of the general
population) are chronically infected with the hepatitis C virus, according to a
study conducted by the World Health Organization (WHO). In Europe, chronic
hepatitis C is the leading cause of chronic liver disease and the most common
reason for liver transplant.

     In the United States, Schering-Plough on Dec. 23, 1999, submitted a
Biologics License Application (BLA) to the U.S. Food and Drug Administration
(FDA) seeking marketing approval for






     PEG-INTRON(TM) (peginterferon alfa-2b) Powder for Injection for the
treatment of chronic hepatitis C in patients 18 years of age or older with
compensated liver disease. The application proposes administration of PEG-INTRON
subcutaneously once weekly for one year. Some 4 million Americans are
chronically infected with the hepatitis C virus, according to the Centers for
Disease Control and Prevention (CDCP).

     PEG-INTRON is also in Phase III clinical trials as combination therapy with
REBETOL(R) (ribavirin, USP) for hepatitis C. In addition, PEG-INTRON is in Phase
III clinical trials for two cancer indications, malignant melanoma and chronic
myelogenous leukemia (CML), as well as in early stage trials for various solid
tumors.

     Enzon is a biopharmaceutical company developing advanced therapeutics for
life-threatening diseases through the application of its proprietary drug
delivery and targeting technologies, PEG Modification, Pro Drug/Transport
technology and Single-Chain Antigen-Binding (SCA(R)) Protein technology. Enzon's
research activities are focused primarily in the area of oncology. In addition
to two FDA approved products, Enzon has several products in various stages of
clinical development by itself and with partners. Enzon develops and markets
products on its own and through its alliance partners, which in addition to
Schering-Plough include Alexion Pharmaceuticals, Baxter Healthcare, Bristol-
Myers Squibb, Eli Lilly, and Rhone-Poulenc Rorer Pharmaceuticals.

     Certain statements made in this press release related to potential
government approvals, market potential, commercialization and sales revenues of
medical products and biologics, as well as their therapeutic applications and
outcomes, are forward-looking and are made pursuant to the safe harbor
provisions of the Securities Litigation Reform Act of 1995. Such statements
involve risks and uncertainties, which may differ materially from those set
forth in these statements. In addition, the economic, competitive, governmental,
technological and other factors identified in the Company's filings with the
Securities and Exchange Commission could affect such results.

(1)  Elevated enzyme levels indicating ongoing liver inflammation.

(2)  HCV-RNA: hepatitis C viral RNA (ribonucleic acid).

(3)  Anti-HCV: antibodies to hepatitis C virus.

             This release is also available at http://www.enzon.com
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