PROSPECTUS SUPPLEMENT NO. 12                    Filed pursuant to Rule 424(b)(3)
(To prospectus dated October 24, 2001)                Registration No. 333-67506


                                  $400,000,000
                                   Enzon, Inc.

                 4 1/2% Convertible Subordinated Notes Due 2008

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

This Prospectus Supplement No. 12 supplements and amends the Prospectus dated
October 24, 2001 relating to the 4 1/2% Convertible Subordinated Notes due 2008
of Enzon, Inc. and the shares of common stock into which the notes are
convertible, at various times at market prices prevailing at the time of sale or
at privately negotiated prices.

The table on pages 38 through 40 of the prospectus, which sets forth information
with respect to the selling holders and the respective amounts of notes
beneficially owned by each selling holder, is hereby amended as follows:

    The addition of the following:

      BTES-Convertible Arb...........................................$2,000,000

      BTPO Growth Vs Value...........................................$7,000,000

The Prospectus, together with Prospectus Supplement Nos. 1, 2, 3, 4, 5, 6, 7, 8,
9, 10 and 11 and this Prospectus Supplement No. 12, constitutes the prospectus
required to be delivered by Section 5(b) of the Securities Act of 1933, as
amended, with respect to offers and sales of the notes and the common stock
issuable upon conversion of the notes. All reference in the prospectus to "this
prospectus" are hereby amended to read "this prospectus (as supplemented and
amended)".

Neither the Securities and Exchange Commission nor any state securities
commission has approved or disapproved of these securities or passed upon the
accuracy or adequacy of this prospectus. Any representation to the contrary is a
criminal offense.

          The date of this Prospectus Supplement is November 22, 2002.