ENZON INC
10-Q, 1997-05-15
BIOLOGICAL PRODUCTS, (NO DIAGNOSTIC SUBSTANCES)
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                       SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549

                                    FORM 10-Q


                QUARTERLY REPORT UNDER SECTION 13 OR 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

For Quarter Ended March 31, 1997                     Commission File No. 0-12957
                  --------------                               -------


                                   ENZON, INC.
             (Exact name of registrant as specified in its charter)



               Delaware                                        22-2372868
(State or other jurisdiction of                                (IRS Employer
 incorporation or organization)                             Identification No.)

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

                                 (908) 980-4500
              (Registrant's telephone number, including area code:)



Indicate by check mark whether the registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the  preceding 12 months (or for such  shorter  period that the  registrant  was
required  to file  such  reports),  and  (2) has  been  subject  to such  filing
requirements for the past 90 days.


Yes   X    No


The number of shares of common stock,  $.01 par value,  outstanding as of May 7,
1997 was 30,796,174 shares.

<PAGE>

PART I FINANCIAL INFORMATION
Item 1. Financial Statements


                           ENZON, INC AND SUBSIDIARIES
                      CONSOLIDATED CONDENSED BALANCE SHEETS
                        March 31, 1997 and June 30, 1996

<TABLE>
<CAPTION>

                                                                           March 31,                     June 30,
ASSETS                                                                       1997                          1996
                                                                 ------------------------------------------------------------
                                                                          (unaudited)                       *
Current assets:
<S>                                                                             <C>                             <C>        
  Cash and cash equivalents                                                     $9,596,973                      $12,666,050
  Accounts receivable                                                            2,326,397                        2,123,691
  Inventories                                                                      891,275                          985,378
  Other current assets                                                             123,048                          434,318
                                                                             -------------                    -------------
     Total current assets                                                       12,937,693                       16,209,437
                                                                              ------------                     ------------
Property and equipment                                                          15,671,729                       15,640,823
  Less accumulated depreciation and amortization                                12,643,514                       11,617,690
                                                                              ------------                     ------------
                                                                                 3,028,215                        4,023,133
                                                                             -------------                    -------------
Other assets:
  Investments                                                                       78,293                           78,293
  Other assets, net                                                                 63,805                           55,945
  Patents, net                                                                   1,481,188                        1,597,048
                                                                              ------------                     ------------
                                                                                 1,623,286                        1,731,286
                                                                              ------------                     ------------
Total assets                                                                   $17,589,194                      $21,963,856
                                                                               ===========                     ============
LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities:
  Accounts payable                                                              $1,910,902                       $2,078,924
  Accrued expenses                                                               3,714,457                        4,387,052
                                                                               -----------                     ------------
     Total current liabilities                                                   5,625,359                        6,465,976
                                                                              ------------                    -------------
  Accrued rent                                                                     901,672                          980,908
  Royalty advance - RPR                                                          1,404,505                        1,600,786
  Other liabilities                                                                  -                                1,728
                                                                         -----------------                   --------------
                                                                                 2,306,177                        2,583,422
                                                                              ------------                     ------------
Commitments and contingencies
Stockholders' equity:
  Preferred  stock-$.01  par  value,  authorized  3,000,000  shares:  issued and
   outstanding  109,000  shares at March 31, 1997 and 169,000 shares at June 30,
   1996 (liquidating preference aggregating $2,725,000 at March 31, 1997 and
   $8,725,000 at June 30, 1996)                                                      1,090                            1,690
  Common stock-$.01 par value, authorized 40,000,000 shares;
   issued and outstanding 30,789,930 shares at March
   31, 1997 and 27,706,396 shares at June 30, 1996                                 307,899                          277,064
  Additional paid-in capital                                                   121,406,237                      121,272,024
  Accumulated deficit                                                        (112,057,568)                    (108,636,320)
                                                                             -------------                    -------------
Total stockholders' equity                                                       9,657,658                       12,914,458
                                                                             -------------                    -------------
Total liabilities and stockholders' equity                                     $17,589,194                      $21,963,856
                                                                              ============                     ============
</TABLE>

*Condensed from audited financial statements.

The  accompanying  notes are an integral  part of these  unaudited  consolidated
condensed financial statements.

                                                       - 2 -

<PAGE>

                                   ENZON, INC.
                 CONSOLIDATED CONDENSED STATEMENTS OF OPERATIONS
           Three Months and Nine Months Ended March 31, 1997 and 1996
                                   (Unaudited)

<TABLE>
<CAPTION>

                                                        Three months ended                            Nine months ended
                                                 March 31,             March 31,            March 31,              March 31,
                                                    1997                  1996                  1997                   1996

                                               ------------------------------------------------------------------------------------
Revenues
<S>                                                <C>                    <C>                   <C>                     <C>       
  Sales                                            $2,350,113             $2,729,647            $8,624,679              $8,080,671
  Contract revenue                                     31,758                  5,710             1,131,067                 910,446
                                               --------------             ----------            ----------             -----------
     Total revenues                                 2,381,871              2,735,357             9,755,746               8,991,117
                                                 ------------           ------------            ----------              ----------
Costs and expenses
  Cost of sales                                     1,070,822                903,985             3,051,136               3,092,562
  Research and development expenses                 2,073,030              2,469,605             6,482,864               7,551,075
  Selling, general and administrative expenses      1,356,249              1,536,058             4,085,861               4,212,378
                                                   ----------             ----------            ----------              ----------
     Total costs and expenses                       4,500,101              4,909,648            13,619,861              14,856,015
                                                   ----------             ----------           -----------             -----------
       Operating loss                             (2,118,230)            (2,174,291)           (3,864,115)             (5,864,898)
                                                -------------           ------------          ------------            ------------
Other income (expense)
  Interest and dividend income                        113,641                116,259               433,552                 300,338
  Interest expense                                    (2,613)                (1,801)              (14,213)                (12,753)
  Other                                                15,413                 65,369                23,528               1,386,691
                                                 ------------            -----------         -------------              ----------
                                                      126,441                179,827               442,867               1,674,276
                                                   ----------             ----------           -----------              ----------
     Net loss                                    ($1,991,789)           ($1,994,464)          ($3,421,248)            ($4,190,622)
                                                 ============           ============          ============            ============
Net loss per common share                             ($0.07)                ($0.08)               ($0.13)                 ($0.16)
                                                      =======                =======               =======                 =======

Weighted average number of common
 shares outstanding during the period              29,798,374             26,929,341            28,462,602              26,529,030
                                                  ===========             ==========           ===========              ==========

</TABLE>

The  accompanying  notes are an integral  part of these  unaudited  consolidated
condensed financial statements.

                                      - 3 -

<PAGE>

                          ENZON, INC. AND SUBSIDIARIES
                 CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS
                    Nine Months Ended March 31, 1997 and 1996
                                   (Unaudited)

<TABLE>
<CAPTION>
                                                                                           Nine Months Ended

                                                                                     March 31,              March 31,
                                                                                       1997                   1996
                                                                           -------------------------------------------------
Cash flows from operating activities:
<S>                                                                                    <C>                  <C>         
  Net loss                                                                             ($3,421,248)         ($4,190,622)
  Adjustment for decrease in liability recognized pursuant
    to Sanofi Winthrop Agreement                                                                  -          (1,312,829)
  Adjustment for depreciation and amortization                                            1,282,515            1,565,134
  Non-cash expense for issuance of common stock and stock options                           137,841                    -
  Gain on sale of equipment                                                                (15,413)                    -
  Decrease in accrued rent                                                                 (79,236)             (15,379)
  Decrease in royalty advance - RPR                                                       (602,455)            (323,038)
  Changes in assets and liabilities                                                       (239,630)            (448,401)
                                                                                     --------------        -------------
  Net cash used in operating activities                                                 (2,937,626)          (4,725,135)
                                                                                      -------------         ------------
Cash flows from investing activities:
  Capital expenditures                                                                    (817,050)             (93,732)
  Proceeds from sale of equipment                                                           660,726               -
                                                                                       ------------              ------
  Net cash used in investing activities                                                   (156,324)             (93,732)
                                                                                      -------------         ------------
Cash flows from financing activities:
  Proceeds from issuance of common and preferred stock                                       26,607            9,478,591
  Principal payments of obligation under capital leases                                     (1,734)              (1,539)
                                                                                    ---------------       --------------
  Net cash provided by financing activities                                                  24,873            9,477,052
                                                                                    ---------------         ------------
  Net (decrease) increase in cash and cash equivalents                                  (3,069,077)            4,658,185
  Cash and cash equivalents at beginning of period                                       12,666,050            8,102,989
                                                                                       ------------           ----------
  Cash and cash equivalents at end of period                                             $9,596,973          $12,761,174
                                                                                         ==========          ===========
</TABLE>


The  accompanying  notes are an integral  part of these  unaudited  consolidated
condensed financial statements.

                                      - 4 -

<PAGE>

                          ENZON, INC. AND SUBSIDIARIES
              Notes To Consolidated Condensed Financial Statements
                                   (Unaudited)

(1)  Organization and Basis of Presentation

         The unaudited  consolidated  condensed  financial  statements have been
prepared  from the  books  and  records  of  Enzon,  Inc.  and  subsidiaries  in
accordance with generally accepted  accounting  principles for interim financial
information.  Accordingly,  they  do not  include  all of  the  information  and
footnotes  required by generally  accepted  accounting  principles  for complete
financial statements. In the opinion of management,  all adjustments (consisting
only of  normal  and  recurring  adjustments)  considered  necessary  for a fair
presentation  have been included.  Certain prior year balances were reclassified
to  conform  to the  1997  presentation.  Interim  results  are not  necessarily
indicative of the results that may be expected for the year.

(2)  Net Loss Per Common Share

         Net loss  per  common  share is based on the net loss for the  relevant
period, adjusted for cumulative undeclared preferred stock dividends of $164,000
for each of the nine months ended March 31, 1997 and 1996,  and $55,000 for each
of the three  months  ended  March 31,  1997 and 1996,  divided by the  weighted
average  number of shares  issued  and  outstanding  during  the  period.  Stock
options,  warrants and common stock  issuable  upon  conversion of the preferred
stock are not reflected as their effect would be  antidilutive  for both primary
and fully diluted earnings per share computations.

(3)  Inventories

         The  composition  of inventories at March 31, 1997 and June 30, 1996 is
as follows:

                                  March 31,                     June 30,
                                    1997                           1996

         Raw materials              $336,000                  $206,000
         Work in process             198,000                   383,000
         Finished goods              357,000                   396,000
                                     -------                   -------
                                    $891,000                  $985,000
                                    ========                  ========

(4)  Cash Flow Information

         The  Company  considers  all highly  liquid  securities  with  original
maturities  of three months or less to be cash  equivalents.  Cash  payments for
interest were approximately  $14,000 and $13,000 for the nine months ended March
31, 1997 and 1996, respectively.  There were no income tax payments made for the
nine months ended March 31, 1997 and 1996.

         During the nine months ended March 31, 1997,  40,000 shares of Series B
Convertible  Preferred  Stock  ("Series B Preferred  Stock") were converted into
2,038,989  shares  of  Common  Stock.  A cash  payment  of  $3.00  was  made for
fractional shares related to the conversions. During the quarter ended March 31,
1997, the Company's  Series C Convertible  Preferred  Stock ("Series C Preferred
Stock") was  exchanged  for 20,000  shares of newly issued  Series D Convertible
Preferred  Stock  ("Series D Preferred  Stock").  The 20,000  shares of Series D
Preferred Stock were converted into 1,015,228  shares of Common Stock during the
quarter  ended March 31, 1997.  A cash payment of $1.00 was made for  fractional
shares  related to the  conversion of the Series D Preferred  Stock.  During the
nine months ended March 31, 1996, the Company issued 150,000 five-year  warrants
to  purchase  the  Company's  common  stock  at $2.50  per  share as part of the
commission due to the real estate broker in connection  with the  termination of
the lease at 40 Kingsbridge  Road.  These  transactions  are non-cash  financing
activities.

                                      - 5 -

<PAGE>

                          ENZON, INC. AND SUBSIDIARIES
         Notes To Consolidated Condensed Financial Statements, Continued
                                   (Unaudited)


(5) Significant Agreements

         During  October 1996,  the Company  entered into a marketing  agreement
with Medac GmbH ("MEDAC") to sell  ONCASPAR(R) in Europe and Russia.  MEDAC will
purchase ONCASPAR from Enzon at a set price which will increase over the term of
the agreement.  The agreement  also contains  certain  minimum  annual  purchase
requirements.

(6) Non-Qualified Stock Option Plan

         During  the nine  months  ended  March 31,  1997,  the  Company  issued
1,167,625  stock options at an average  exercise  price of $2.80 per share under
the Company's Non-Qualified Stock Option Plan, as amended (the "Plan"), of which
290,000  were granted to executive  officers of the Company.  The stock  options
issued include  310,000  options which were granted to independent  directors of
the  Company,  under  the  Plan's  automatic  grant  provisions  to  independent
directors.  None of the options  granted during the period are exercisable as of
March 31, 1997.  All options were granted with  exercise  prices that equaled or
exceeded the fair market value of the underlying stock on the date of grant.

(7) Stockholders' Equity

         During the nine months  ended March 31,  1997,  all of the  outstanding
shares of Series B Preferred Stock were converted into Common Stock.  The 40,000
shares of Series B Preferred Stock which were converted resulted in the issuance
of 2,038,989 shares of Common Stock.

         During the quarter ended March 31, 1997, all of the outstanding  Series
C Preferred Stock was exchanged for newly issued Series D Preferred  Stock.  The
Series D Preferred  Stock contains the same provisions as the Series C Preferred
Stock,  with the exception of the  elimination  of a restriction  on the maximum
number of shares held by the holding institution.  During March 1997, all of the
outstanding Series D Preferred Stock was converted into Common Stock. The 20,000
shares of Series D Preferred Stock which were converted resulted in the issuance
of 1,015,228 shares of Common Stock. The sole institutional  owner of the Common
Stock issued in conjunction  with the conversion of the Series D Preferred Stock
has agreed not to sell the  1,015,228  common  shares issued for a period of one
year without the Company's consent.

         During the nine months ended March 31, 1997,  the Company issued 18,098
shares  of  Enzon  common  stock to  non-executive  directors,  pursuant  to the
Company's Independent Directors' Stock Plan. The shares issued represent payment
for services  rendered for the period from January 16, 1996 through December 31,
1996.

                                      - 6 -

<PAGE>

                          ENZON, INC. AND SUBSIDIARIES
         Notes To Consolidated Condensed Financial Statements, Continued
                                   (Unaudited)


(8) Operating Lease

     During March 1997, the Company entered into a  sale-leaseback  agreement to
fund up to $800,000 in research and development  equipment and related leasehold
improvements.  As of March 31,  1997,  the  Company had  utilized  approximately
$644,000 of the funding available under the agreement. The $644,000 of equipment
financed  during the  quarter  ended March 31,  1997,  was sold at a price which
exceeded  book value and the  corresponding  lease is being  accounted for as an
operating  lease.  The lease  expires  during  September,  2000.  The  remaining
$156,000 under the agreement can be used to finance future purchases of research
and development  equipment  through December 31, 1997. As of March 31, 1997, the
future minimum lease payments under the agreement are as follows:

    Year ending
      June 30,
      --------
        1997          $                 36,000
        1998                           217,000
        1999                           217,000
        2001                            36,000
                                       723,000
                                       -------

(9) Other Income

         During the quarter ended December 31, 1995,  the Company  recognized as
other income  approximately  $1,313,000,  representing  the unused portion of an
advance received under a development and license agreement with Sanofi Winthrop,
Inc.  ("Sanofi").  During October 1995, the Company learned that Sanofi intended
to cease development of PEG-SOD  (Dismutec(TM))  due to the product's failure to
show a statistically  significant difference between the treatment group and the
control  group in a pivotal  Phase III  trial.  Due,  in part,  to this  product
failure,  the Company believes it has no further obligations under its agreement
with Sanofi with respect to the $1,313,000  advance and  therefore,  the Company
reversed the amount due Sanofi previously recorded as a current liability.

                                      - 7 -

<PAGE>

Item 2. Management's  Discussion and Analysis of Financial Condition and Results
of Operations

Information contained herein contains "forward-looking  statements" which can be
identified   by   the   use   of   forward-   looking    terminology   such   as
"believes,"expects","may  ", "will",  "should", or "anticipates" or the negative
thereof or other variations thereon or comparable terminology, or by discussions
of strategy.  No assurance can be given that the future  results  covered by the
forward-looking  statements  will be achieved.  The matters set forth in Exhibit
99.0 to the Company's  Annual Report on Form 10-K for the fiscal year ended June
30, 1996,  which is  incorporated  herein by  reference,  constitute  cautionary
statements  identifying  important factors with respect to such forward- looking
statements,  including certain risks and uncertainties,  that could cause actual
results  to  vary  materially   from  the  future  results   indicated  in  such
forward-looking  statements.  Other factors  could also cause actual  results to
vary  materially  from the  future  results  indicated  in such  forward-looking
statements.

Results of Operations

Three months ended March 31, 1997 vs. Three months ended March 31, 1996

Revenues. Revenues for the three months ended March 31, 1997 decreased by 13% to
$2,382,000 as compared to $2,735,000 for the same period in 1996. The components
of  revenues  are  sales  and  contract  revenues.  Sales  decreased  by  14% to
$2,350,000  for the three months ended March 31, 1997 as compared to  $2,730,000
for the same period in the prior year, due to a decrease in ADAGEN(R)  sales and
a  decrease  in  revenues  from  ONCASPAR.  The  decrease  in  ADAGEN  sales  to
$2,069,000,  compared  to  $2,217,000  for the  same  period  in  1996,  was due
primarily  to the timing of  reimbursement  approvals.  The  Company  recognizes
revenues for the sale of ADAGEN when  reimbursement  from third-party  payors is
determined  to be likely.  The Company  anticipates  that  reimbursement  delays
experienced  during  the  quarter  ended  March 31,  1997 will be  substantially
corrected during subsequent quarters.  Sales of ADAGEN for the nine months ended
March 31,  1997  have  remained  at levels  slightly  above the  previous  year.
ONCASPAR,  the Company's  second  approved  product,  is marketed in the U.S. by
Rhone-Poulenc  Rorer  Pharmaceuticals,  Inc. ("RPR") and in Europe and Russia by
MEDAC GmbH ("MEDAC").  ONCASPAR revenues are comprised of manufacturing revenues
received  from RPR and MEDAC,  as well as royalties on sales of ONCASPAR by RPR.
The  decrease in ONCASPAR  revenues  was due to the timing of  shipments to RPR.
During  the  quarter  ended  December  31,  1996,  shipments  made  to RPR  were
approximately  twice  those made during the same  period in the  previous  year,
resulting  in reduced RPR  requirements  for ONCASPAR  during the quarter  ended
March  31,  1997.  Reductions  in RPR  shipments  were  partially  offset by the
commencement of shipments of ONCASPAR to MEDAC for the European market. Contract
revenue  for the three  months  ended March 31, 1997  increased  to $32,000,  as
compared to $6,000 for the same period in 1996.  During the three  months  ended
March 31, 1997 and 1996,  the Company had export sales of $661,000 and $419,000,
respectively.  Sales in Europe were  $556,000  and $356,000 for the three months
ended March 31, 1997 and 1996,  respectively.  The increase in export as well as
European  sales was due to the  commencement  of  shipments  of ONCASPAR for the
European market.

Cost of Sales. Cost of sales, as a percentage of sales, increased to 46% for the
three  months  ended  March 31,  1997 as  compared to 33% for the same period in
1996. The increase was due primarily to the write-off of approximately  $402,000
in excess ONCASPAR raw material.  The Company has a minimum purchase requirement
under a long-term supply agreement for this material.  While it is possible that
the Company may incur similar losses on its remaining purchase commitments under
the supply  agreement,  the Company does not consider such losses probable,  nor
can the amount of any loss which may be  incurred  in the  future  presently  be
estimated due to a number of factors,  including,  but not limited to, potential
increased  demand for  ONCASPAR  from RPR,  expansion  into  additional  markets
outside the U.S. and the  possibility  that the Company  could  renegotiate  the
level of required purchases.  If the Company does not achieve increases in sales
of ONCASPAR beyond current levels or cannot  renegotiate its commitment,  a loss
would be incurred on the remaining purchase commitment. During the quarter ended
March 31, 1997,  the Company  utilized  approximately  19% of its  manufacturing
capacity for the production of its approved products.

                                      - 8 -

<PAGE>
Research and Development. Research and development expenses for the three months
ended March 31, 1997 decreased by 16% to $2,073,000 from $2,470,000 for the same
period in 1996.  This  decrease was primarily due to reductions in personnel and
related  costs,  such as  payroll  taxes and  benefits,  totaling  approximately
$368,000, due to cost containment measures implemented by the Company as part of
a continued focus on key development programs.

Selling,   General   and   Administrative   Expenses.   Selling,   general   and
administrative  expenses for the three months ended March 31, 1997  decreased by
12% to $1,356,000,  as compared to $1,536,000 for the same period in 1996.  This
decrease was primarily due to reductions in personnel and related costs, such as
payroll taxes and benefits, totaling approximately $252,000.

Other Income/Expense.  Other income/expense decreased by $54,000 to $126,000 for
the three  months  ended March 31,  1997 as  compared  to $180,000  for the same
period last year. The decrease was due  principally to the one-time  recognition
as other  income of  approximately  $65,000  during the quarter  ended March 31,
1996, representing an insurance settlement.

Nine months ended March 31, 1997 vs. Nine months ended March 31, 1996

Revenues.  Revenues for the nine months ended March 31, 1997  increased by 9% to
$9,756,000 as compared to $8,991,000 for the same period in 1996. The components
of revenues are sales and contract revenues. Sales increased by 7% to $8,625,000
for the nine months ended March 31, 1997 as compared to $8,081,000  for the same
period in the prior year, primarily due to increased ONCASPAR revenues. ONCASPAR
revenues are  comprised of  manufacturing  revenues  received from the Company's
marketing partners,  RPR and MEDAC, as well as royalties on sales of ONCASPAR by
RPR.  ONCASPAR  revenues  increased  due to the  commencement  of  shipments  of
ONCASPAR to MEDAC for the European  market,  as well as an increase in royalties
from RPR.  ADAGEN  sales for the nine months  ended March 31, 1997 and 1996 were
$6,523,000 and $6,431,000,  respectively.  Contract  revenue for the nine months
ended March 31, 1997 increased by 24% to $1,131,000, as compared to $910,000 for
the same period in 1996.  Contract  revenues for the nine months ended March 31,
1997 were principally  comprised of a one-time  $1,000,000 payment received from
Schering  Corporation  ("Schering")  related to the transfer of know-how for the
manufacturing  of  PEG-Intron A under the Company's  June 1995 amended  Schering
agreement.  Contract  revenues for the prior year's period  reflected a one-time
payment  received in connection with a worldwide  non-exclusive  license for the
Company's SCA protein  technology  signed with RPR. During the nine months ended
March 31,  1997 and  1996,  the  Company  had  export  sales of  $1,832,000  and
$1,550,000, respectively. Sales in Europe were $1,547,000 and $1,339,000 for the
nine months ended March 31, 1997 and 1996, respectively.  The increase in export
and European sales was due to the  commencement of shipments of ONCASPAR for the
European market.

Cost of Sales.  Cost of sales,  as a percentage  of sales,  remained  relatively
consistent  at 35% for the nine months ended March 31, 1997,  as compared to 38%
for the same period in 1996.

Research and Development.  Research and development expenses for the nine months
ended March 31, 1997 decreased by 14% to $6,483,000 from $7,551,000 for the same
period in 1996.  This  decrease was  primarily  due to  reductions in personnel,
principally in the clinical and  scientific  administration  areas,  and related
costs,  such as payroll taxes,  totaling  approximately  $911,000 and other cost
containment  measures implemented by the Company as part of a continued focus on
key development programs.

Selling,   General   and   Administrative   Expenses.   Selling,   general   and
administrative  expenses  for the nine  months  ended  March 31,  1997  remained
relatively  consistent at  $4,086,000,  as compared to  $4,212,000  for the same
period in 1996.

                                      - 9 -

<PAGE>
Other Income/Expense.  Other income/expense  decreased by $1,231,000 to $443,000
for the nine months ended March 31, 1997 as compared to $1,674,000  for the same
period last year. The decrease was due  principally to the one-time  recognition
as other income of  approximately  $1,313,000  during the quarter ended December
31,  1995,  representing  the  unused  portion of an  advance  received  under a
development and license agreement with Sanofi.

         In February  1997,  the  Financial  Accounting  Standards  Board issued
Statements of Financial  Accounting  Standards No. 128 (SFAS  128),"Earnings Per
Share". SFAS 128 establishes standards for computing and presenting earnings per
share. In accordance with the effective date of SFAS 128, the Company will adopt
SFAS 128 as of December  31,  1997.  This  statement  is not  expected to have a
material impact on the Company's consolidated financial statements.

Liquidity and Capital Resources

         Enzon had $9,597,000 in cash and cash equivalents as of March 31, 1997.
The Company  invests its excess cash in a  portfolio  of  high-grade  marketable
securities and United States government-backed securities.

         The  Company's  cash  reserves  as  of  March  31,  1997  decreased  by
$3,069,000  from June 30, 1996.  The decrease in cash reserves was caused by the
funding of operations as well as capital  expenditures  of $817,000,  related to
the upgrade of the Company's pilot  manufacturing  facility for  PEG-hemoglobin,
which  were  partially  offset by the  sale-leaseback  of certain  research  and
development equipment purchased during the period.

         The Company's  exclusive  U.S.  marketing  rights  license with RPR for
ONCASPAR  provides for a payment of  $3,500,000 in advance  royalties  which was
received in January 1995.  Under the  agreement,  as amended,  royalties will be
offset against a credit of $5,970,000, which represents the royalty advance plus
reimbursement  of  certain  amounts  due RPR under the  previous  agreement  and
interest  expense,  before cash payments will be made under the  agreement.  The
royalty advance is shown as a long term liability with the corresponding current
portion  included in accrued  expenses  on the  consolidated  condensed  balance
sheets and will be reduced as  royalties  are  recognized  under the  agreement.
Through March 31, 1997,  an aggregate of $2,073,000 in royalties  payable by RPR
have been offset against the original credit.

         As of March 31, 1997, 940,808 shares of Series A Cumulative Convertible
Preferred Stock ("Series A Preferred  Stock") have been converted into 3,093,411
shares of the Company's common stock (the "Common Stock").  Accrued dividends on
the  converted  Series A Preferred  Stock in the  aggregate of  $1,792,000  were
settled by the issuance of 232,383 shares of Common Stock.  The Company does not
presently  intend to pay cash dividends on the Series A Preferred  Stock.  As of
March 31, 1997,  there were  $1,531,000  of accrued and unpaid  dividends on the
Series A Preferred Stock. These dividends are payable in cash or Common Stock at
the Company's  option and accrue on the outstanding  Series A Preferred Stock at
the rate of  $218,000  per year.  During the nine months  ended March 31,  1997,
40,000  shares of the Company's  Series B Preferred  Stock were  converted  into
2,038,989  shares of Common Stock.  During the nine months ended March 31, 1997,
20,000  shares of the Company's  Series C Preferred  Stock were  converted  into
20,000 shares of Series D Preferred Stock which were subsequently converted into
1,015,228 shares of Common Stock.

         To date, the Company's  sources of cash have been the proceeds from the
sale of its stock through public and private placements,  sales of ADAGEN, sales
of ONCASPAR, sales of its products for research purposes,  contract research and
development fees, technology transfer and license fees and royalty advances. The
Company's  current  sources of  liquidity  are its cash,  cash  equivalents  and
interest earned on such cash reserves, sales of ADAGEN, sales of ONCASPAR, sales
of its products for research purposes and license fees. Management believes that
its current sources of liquidity will be sufficient to meet its anticipated cash
requirements,  based on current spending levels,  for approximately the next two
years.
                                     - 10 -

<PAGE>
         Upon exhaustion of the Company's  current cash reserves,  the Company's
continued  operations will depend on its ability to realize significant revenues
from the commercial sale of its products,  raise additional funds through equity
or debt  financing,  or obtain  significant  licensing,  technology  transfer or
contract  research and  development  fees.  There can be no assurance that these
sales, financings or revenue generating activities will be successful.

Item 3. Quantitative and Qualitative Disclosures About Market Risk

         Not applicable.

                                     - 11 -

<PAGE>
PART II OTHER INFORMATION

Item 2. Changes in Securities

         During the period from  November 19, 1996 through  March 31, 1997,  the
purchaser of 40,000 shares of the Company's Series B Convertible Preferred Stock
converted an aggregate of 40,000 shares of such Series B  Convertible  Preferred
Stock  into an  aggregate  of  2,038,989  shares  of  Common  Stock at per share
conversion prices ranging from $1.83 to $2.44.

         On February 28, 1997,  the  purchaser of 20,000 shares of the Company's
Series C Convertible  Preferred Stock exchanged such shares for 20,000 shares of
newly  issued  Series D  Convertible  Preferred  Stock.  The  shares of Series C
Convertible  Preferred  Stock were retired.  The Series D Convertible  Preferred
Stock contains the same provisions as the Series C Convertible  Preferred Stock,
except that the  restriction on the maximum number of shares that can be held by
the  converting  institution  was  eliminated.  On February 28, 1997, all of the
Series D Convertible  Preferred Stock issued was converted into 1,015,228 shares
of  Common  Stock  at a per  share  conversion  price of $1.97  per  share.  The
conversion prices for the Series B Convertible  Preferred Stock and the Series D
Convertible  Preferred Stock were equal to 80% of the average of the closing bid
prices of the Common  Stock for the five  consecutive  trading  days  ending one
trading day prior to the date of such  conversion.  The Company  relied upon the
exemption  from  registration  under the  Securities  Act of 1933,  as  amended,
contained in (i) Section 4(2) thereof with respect to the issuance of the Series
D Convertible Preferred Stock in exchange for the Series C Convertible Preferred
Stock and (ii)  Section  3(a)(9)  thereof  with  respect to the issuance of such
shares of Common Stock upon  conversion  of the Series B  Convertible  Preferred
Stock and the Series D Convertible Preferred Stock.

                                     - 12 -

<PAGE>
Item 6. Exhibits and Reports on Form 8-K

         (a) Exhibits (numbered in accordance with Item 601 of Regulation S-K).

<TABLE>
<CAPTION>

  Exhibit                                                                                                 Page Number
   Number               Description                                                                           or
                                                                                                        Incorporation
                                                                                                         By Reference
<S>     <C>                                                                                             
        3(i)   Certificate of Incorporation, as amended                                                ^
       3(ii)   By-laws, as amended                                                                     *(4.2)
      3(iii)   Certificate of Designations, Preferences and Rights of Series D
                        Convertible Preferred Stock                                                    o
        10.0   Employment Agreement dated March 25, 1994 with Peter G. Tombros                         #(10.17)
        10.1   Form of Change of Control Agreements dated as of January 20, 1995 entered
                 into with the Company's Executive Officers                                            ~(10.2)
        10.2   Lease - 300-C Corporate Court, South
                        Plainfield, New Jersey                                                         ***(10.3)
        10.3   Modification of Lease - 300-C Corporate Court, South Plainfield
                        New Jersey                                                                     ++(10.3)
        10.4   Lease Termination Agreement dated March 31, 1995 for
                 20 Kingsbridge Road and 40 Kingsbridge Road, Piscataway, New Jersey                   ~(10.6)
        10.5   Option Agreement dated April 1, 1995 regarding 20 Kingsbridge Road,
                 Piscataway, New Jersey                                                                ~(10.7)
        10.6   Form of Lease - 40 Cragwood Road, South
                        Plainfield, New Jersey                                                         ****(10.9)
        10.7   Lease 300A-B Corporate Court, South Plainfield, New Jersey                              +++(10.10)
        10.8   Stock Purchase Agreement dated March 5, 1987
                        between the Company and Eastman Kodak Company                                  ****(10.7)
        10.9   Amendment dated June 19, 1989 to Stock Purchase
                        Agreement between the Company and
                        Eastman Kodak Company                                                          **(10.10)
       10.10   Form of Stock Purchase Agreement between the Company
                        and the purchasers of the Series A Cumulative
                        Convertible Preferred Stock                                                    +(10.11)
       10.11   Amendment to License Agreement and Revised License Agreement
                        between the Company and RCT dated
                        April 25, 1985                                                                 ++++(10.5)
       10.12   Amendment dated as of May 3, 1989 to Revised License Agreement
                        dated April 25, 1985 between the Company and Research
                        Corporation                                                                    **(10.14)
       10.13   License Agreement dated September 7, 1989 between the Company and
                Research Corporation Technologies, Inc.                                                **(10.15)
       10.14   Master Lease Agreement and Purchase Leaseback Agreement dated
                        October 28, 1994 between the Company and Comdisco, Inc.                        ##(10.16)
       10.15   Amendment dated as of May 15, 1995 to Employment Agreement with
                        Peter G. Tombros                                                               ~~(10.17)
       10.16   Stock Purchase Agreement dated as of June 30, 1995                                      ~~~(10.16)
       10.17   Securities Purchase Agreement dated as of January 31, 1996                              ~~~(10.17)
       10.18   Registration Rights Agreements dated as of January 31, 1996                             ~~~(10.18)
       10.19   Warrants dated as of February 7, 1996 and issued pursuant to the Securities
                        Purchase Agreement dated as of January 31, 1996                                ~~~(10.19)
       10.20   Securities Purchase Agreement dated as of March 15, 1996                                ^(10.20)


                                     - 13 -
</TABLE>

<PAGE>

<TABLE>
<CAPTION>

<S>    <C>                                                     <C> <C>                                  <C>    
       10.21   Registration Rights Agreement dated as of March 15, 1996                                ^(10.21)
       10.22   Warrant dated as of March 15, 1996 and issued pursuant to the Securities
                         Purchase Agreement dated as of March 15, 1996                                 ^(10.22)
       10.23   Amendment dated March 25, 1994 to License Agreement dated
                September 7, 1989 between the Company and Research Corporation
                Technologies, Inc.                                                                     ^^^(10.23)
       10.24   Independent Directors' Stock Plan                                                       ^^^(10.24)
       10.25   Stock Exchange Agreement dated February 28, 1997, by and between
                        the Company and GFL Performance Fund Ltd.                                      o
       10.26   Agreement Regarding Registration Rights Under Registration Rights
                        Agreement dated March 10, 1997, by and between the Company and
                        Clearwater Fund IV LLC                                                         o
        27.0   Financial Data Schedule                                                                 o
        99.0   Factors to Consider in Connection with Forward-Looking Statements                       ^^(99.0)

</TABLE>

o    Filed herewith.

*    Previously filed as an exhibit to the Company's  Registration  Statement on
     Form S-2 (File No. 33- 34874) and incorporated herein by reference thereto.

**   Previously  filed as exhibits to the  Company's  Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1989  and  incorporated  herein  by
     reference thereto.

***  Previously filed as an exhibit to the Company's  Registration  Statement on
     Form S-18  (File  No.  2-88240-NY)  and  incorporated  herein by  reference
     thereto.

**** Previously  filed as exhibits to the  Company's  Registration  Statement on
     Form S-1 (File No. 2- 96279)  filed with the  Commission  and  incorporated
     herein by reference thereto.

+    Previously filed as an exhibit to the Company's  Registration  Statement on
     Form S-1 (File No. 33- 39391) filed with the  Commission  and  incorporated
     herein by reference thereto.

++   Previously  filed as an exhibit to the Company's Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1992  and  incorporated  herein  by
     reference thereto.

+++  Previously  filed as an exhibit to the Company's Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1993  and  incorporated  herein  by
     reference thereto.

++++ Previously  filed as an exhibit to the Company's Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1985  and  incorporated  herein  by
     reference thereto.

#    Previously filed as an exhibit to the Company's  Current Report on Form 8-K
     dated April 5, 1994 and incorporated herein by reference thereto.

##   Previously  filed as an exhibit to the Company's  Quarterly  Report on Form
     10-Q for the quarter  ended  December 31, 1994 and  incorporated  herein by
     reference thereto.

~    Previously  filed as an exhibit to the Company's  Quarterly  Report on Form
     10-Q for the  quarter  ended  March  31,  1995 and  incorporated  herein by
     reference thereto.

~~   Previously  filed as an exhibit to the Company's Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1995  and  incorporated  herein  by
     reference thereto.

                                     - 14 -

<PAGE>
~~~  Previously  filed as an exhibit to the Company's  Quarterly  Report on Form
     10-Q for the quarter  ended  December 31, 1995 and  incorporated  herein by
     reference thereto.

^    Previously  filed as an exhibit to the Company's  Quarterly  Report on Form
     10-Q for the  quarter  ended  March  31,  1996 and  incorporated  herein by
     reference thereto.

^^   Previously  filed as an exhibit to the Company's Annual Report on Form 10-K
     for the  fiscal  year  ended  June 30,  1996  and  incorporated  herein  by
     reference thereto.

^^^  Previously  filed as an exhibit to the Company's  Quarterly  Report on Form
     10-Q for the quarter  ended  December 31, 1996 and  incorporated  herein by
     reference thereto.

(b)  Reports on Form 8-K

     On January 16, 1997, the Company filed with the Commission a Current Report
on Form 8-K dated  January 2, 1997  relating to (i) the  appointment  of Rolf A.
Classon to the Company's  Board of Directors  and (ii) a complaint  filed by LBC
Capital Resources, Inc.("LBC") on December 17, 1996.

     On January 27, 1997, the Company filed with the Commission a Current Report
on Form 8-K dated  January  22,  1997  relating  to (i) the  appointment  of Dr.
Jeffrey McGuire to the newly created  position of vice  president,  research and
development and chief scientific  officer and (ii) Dr. Robert Shorr assuming the
position of vice president, science and technology, reporting to Dr. McGuire.

     On February  28,  1997,  the Company  filed with the  Commission  a Current
Report on Form 8-K dated  February 20, 1997 relating to the conversion of all of
the outstanding shares of Series B Convertible Preferred Stock issued in January
1996. The  conversions,  which took place between November 12, 1996 and February
19, 1997 resulted in the issuance of 2,038,989 shares of Common Stock.

     On March 10, 1997,  the Company filed with the  Commission a Current Report
on Form 8-K dated  March 3, 1997  relating to the  exchange of 20,000  shares of
Series C Convertible Preferred Stock into 20,000 shares of newly issued Series D
Convertible Preferred Stock. The 20,000 shares of Series D Convertible Preferred
Stock were subsequently converted into 1,015,228 shares of Common Stock.

                                     - 15 -

<PAGE>

                                   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 thereunto duly authorized.

                                            ENZON, INC.
                                            (Registrant)



Date: May 13, 1997                          By: /S/PETER G. TOMBROS
                                               --------------------
                                            Peter G. Tombros
                                            President and Chief Executive
                                             Officer



                                            By: /S/KENNETH J. ZUERBLIS
                                            Kenneth J. Zuerblis
                                            Vice President, Finance and
                                             Chief Financial Officer

                                     - 16 -


                                                      
                                                      
                                                      

                    CERTIFICATE OF DESIGNATIONS, PREFERENCES

                       AND RIGHTS OF SERIES D CONVERTIBLE

                                 PREFERRED STOCK

                                       OF

                                   ENZON, INC.

         ENZON, Inc. (the "Company"), a corporation organized and existing under
the General Corporation Law of the State of Delaware,  does hereby certify that,
pursuant to  authority  conferred  upon the Board of Directors of the Company by
the Certificate of Incorporation,  as amended,  of the Company,  and pursuant to
Section 151 of the General  Corporation Law of the State of Delaware,  the Board
of Directors of the Company at a meeting duly held on February 27, 1997, adopted
resolutions   providing  for  the   designations,   preferences   and  relative,
participating, optional or other rights, and the qualifications,  limitations or
restrictions thereof, of twenty thousand (20,000) shares of Series D Convertible
Preferred Stock (the "Series D Preferred Shares") of the Company, as follows:

               RESOLVED,  that the Company is  authorized to issue 20,000 shares
          of Series D  Convertible  Preferred  Stock  (the  "Series D  Preferred
          Shares")  which  shall  have  the  following   powers,   designations,
          preferences and other special rights:

                    (1) Dividends.  The holders of the Series D Preferred Shares
               shall not be entitled to dividends.

                    (2) Conversion of Series D Preferred Shares.  The holders of
               the Series D  Preferred  Shares  shall  have the right,  at their
               option, to convert the

                                      1
<PAGE>

               Series D  Preferred  Shares  into  shares of Common  Stock on the
               following terms and conditions:

               (a) Each Series D Preferred  Share  shall be  convertible  at any
          time after the date of issuance (or, if such Series D Preferred  Share
          is called for  redemption,  at any time up to and  including,  but not
          after,  the close of business on the fifth full  business day prior to
          the date fixed for such  redemption,  unless  default shall be made by
          the Company in providing  the funds for the payment of the  redemption
          price),  into fully paid and nonassessable  shares  (calculated to the
          nearest whole share) of Common Stock of the Company as  constituted at
          the time of such conversion,  at the conversion price (the "Conversion
          Price") in effect at the time of conversion  determined as hereinafter
          provided.  Each  Series D  Preferred  Share shall have a value of $100
          (the "Stated Value") for the purpose of such conversion and the number
          of shares of Common  Stock  issuable  upon  conversion  of each of the
          Series D Preferred  Shares shall be  determined by dividing the Stated
          Value thereof by the Conversion Price then in effect.  Every reference
          herein  to  the  Common  Stock  of the  Company  (unless  a  different
          intention is expressed)  shall be to the shares of the Common Stock of
          the Company,  $.01 par value, as such stock exists  immediately  after
          the issuance of the Series D Preferred  Shares provided for hereunder,
          or to stock into which such Common  Stock may be changed  from time to
          time thereafter.

               (b) The  Conversion  Price  shall be eighty  percent  (80%)  (the
          "Conversion Percentage") of $2.4625, subject to adjustment as provided
          herein. If the registration  statement (the "Registration  Statement")
          covering the shares of Common Stock  issuable  upon  conversion of the
          Series D Preferred Shares (the  "Registration  Rights  Agreement") has
          not been  declared  effective  by the  U.S.  Securities  and  Exchange
          Commission ("SEC") within two hundred ten (210) days after the date of
          issuance  of  the  Series  D  Preferred   Shares,  or  if,  after  the
          Registration  Statement has been declared  effective by the SEC, sales
          cannot be made  pursuant to the  Registration  Statement  by reason of
          stop order, the Company's failure to update the Registration Statement
          in accordance  with the rules and regulations of the SEC or otherwise,
          or if the Common Stock is not listed or included for  quotation on the
          National   Association  of  Securities  Dealers  Automated   Quotation
          ("NASDAQ")  National  Market System (the  "NASDAQ-NMS"),  the New York
          Stock Exchange (the "NYSE"), the American Stock Exchange (the "AMEX"),
          or the NASDAQ SmallCap Market (the "NASDAQ SmallCap") then, as partial
          relief for the damages to the holder by reason of any such delay in or
          reduction  of its  ability to sell the shares of Common  Stock  (which
          remedy shall not be exclusive of any other  remedies  available at law
          or in equity,  except that such remedy shall be the  exclusive  remedy
          for any  delay  in the  effectiveness  of the  Registration  Statement
          provided the Registration Statement

                                      - 2 -

<PAGE>
               is declared  effective  by the SEC within 210 days after the date
          of  issuance  of  the  Series  D  Preferred  Shares),  the  Conversion
          Percentage shall be reduced by a number of percentage  points equal to
          three (3) times the sum of:  (i) the  number of months  (prorated  for
          partial  months) after the end of such 210 day period and prior to the
          date the  Registration  Statement  is declared  effective  by the SEC,
          provided,  however, that there shall be excluded from such period (and
          from any period under clause (ii) immediately  below) delays which are
          attributable to changes in the Registration  Statement required by the
          holders of Series D Preferred Stock,  including,  without  limitation,
          changes  in the  plan of  distribution;  (ii)  the  number  of  months
          (prorated  for partial  months) that sales cannot be made  pursuant to
          the  Registration  Statement  (by reason of stop order,  the Company's
          failure  to  update  the   Registration   or   otherwise)   after  the
          Registration  Statement  has been  declared  effective;  and (iii) the
          number of months  (prorated for partial  months) that the Common Stock
          is not listed or included for quotation on the NASDAQ-NMS, NYSE, AMEX,
          or NASDAQ SmallCap after the Registration  Statement has been declared
          effective;  provided that the aggregate  number of months that are the
          basis of a  reduction  in the  Conversion  Percentage  pursuant to the
          foregoing  clauses (i),  (ii) and (iii) shall not exceed  twelve (12).
          (For example, if the Registration  Statement becomes effective one and
          one-half  (1 1/2)  months  after the end of such 210 day  period,  the
          Conversion Percentage would be 75.5% until any subsequent  adjustment;
          if  thereafter  sales could not be made  pursuant to the  Registration
          Statement for a period of two (2) months,  the  Conversion  Percentage
          would then be 69.5%.) If the holder converts Series D Preferred Shares
          into Common Stock and an  adjustment to the  Conversion  Percentage is
          required subsequent to such conversion,  but prior to the sale of such
          Common  Stock by such  holder,  the Company  shall pay to such holder,
          within  five (5) days  after  receipt  of a notice of the sale of such
          Common Stock from such holder,  an amount equal to $1.97 multiplied by
          three-hundredths  (.03)  times  the  number of  months  (prorated  for
          partial  months) for which an adjustment  was required;  provided that
          the  aggregate  number  of  months  for which  such an  adjustment  is
          required  (when added to the number of months for which an  adjustment
          is made  pursuant  to clauses  (i),  (ii) and (iii)  above)  shall not
          exceed twelve (12). Such amount may be paid at the Company's option in
          cash or Common  Stock  valued  based on the Average  Market  Price (as
          hereinafter  defined)  of the Common  Stock for the period of five (5)
          consecutive trading days ending on the date of the sale of such Common
          Stock;  provided,  however,  that any  amounts  due as to that  period
          during  which the shares are not traded or included  for  quotation on
          the  NASDAQ-NMS,  NYSE,  AMEX or NASDAQ SmallCap shall be paid in cash
          only. (For example, if the Conversion Percentage was 75.5% at the time
          of  conversion  of  $1,000,000  in Stated  Value of Series D Preferred
          Shares (such that the Series D Preferred  Shares were  converted  into
          Common Stock having an Average Market Price for the applicable  period
          in aggregate of $1,324,503) and subsequent to conversion

                                      - 3 -

<PAGE>
               there  was a  further  two (2)  month  delay in the  Registration
          Statement's being declared  effective,  and such Common Stock was sold
          at the end of such two (2) month period,  the Company would pay to the
          holder $79,470.20 in cash or Common Stock.)

               "Average  Market  Price" of any  security for any period shall be
          computed as the arithmetic  average of the closing bid prices for such
          security for each trading day in such period on the NASDAQ-NMS, or, if
          the NASDAQ-NMS is not the principal  trading market for such security,
          on the principal trading market for such security, or, if market value
          cannot be calculated  for such period on any of the  foregoing  bases,
          the  average  fair  market  value  during  such  period as  reasonably
          determined in good faith by the Board of Directors of the Company.

               (c) If the  Company  shall  consolidate  with or  merge  into any
          corporation  or  reclassify  its  outstanding  shares of Common  Stock
          (other than by way of subdivision or reduction of such shares) (each a
          "Major  Transaction"),  then  each  Series  D  Preferred  Share  shall
          thereafter  be  convertible  into the  number  of  shares  of stock or
          securities (the "Resulting Securities") or property of the Company, or
          of the entity resulting from such  consolidation or merger, to which a
          holder  of the  number  of  shares  of  Common  Stock  delivered  upon
          conversion  of such Series D Preferred  Share would have been entitled
          upon such Major  Transaction had the holder of such Series D Preferred
          Share exercised its right of conversion and had such Common Stock been
          issued and  outstanding  and had such holder been the holder of record
          of such Common  Stock at the time of such Major  Transaction,  and the
          Company  shall  make  lawful  provision  therefor  as a part  of  such
          consolidation, merger or reclassification; provided, however, that the
          Company  shall  give the  holders  of the  Series D  Preferred  Shares
          written notice of any Major Transaction promptly upon the execution of
          any  agreement   whether  or  not  binding  in  connection   therewith
          (including  without  limitation  a letter of intent  or  agreement  in
          principle)  and in no event shall a Major  Transaction  be consummated
          prior to ninety (90) days after such notice.

               (d) The Company shall not issue any fraction of a share of Common
          Stock  upon any  conversion,  but  shall pay in cash  therefor  at the
          Conversion Price then in effect multiplied by such fraction.

               (e) On  presentation  and  surrender  to the  Company  (or at any
          office or agency maintained for the transfer of the Series D Preferred
          Shares)  of the  certificates  of Series D  Preferred  Shares so to be
          converted,  duly  endorsed  in blank for  transfer or  accompanied  by
          proper  instruments  of assignment or transfer in blank (a "Conversion
          Notice"),  with  signatures  guaranteed,  the holder of such  Series D
          Preferred Shares shall be entitled,

                                      - 4 -

<PAGE>

               subject  to the  limitations  herein  contained,  to  receive  in
          exchange  therefor a certificate  or  certificates  for fully paid and
          nonassessable  shares,  which  certificates  shall be delivered by the
          second  trading  day  after  the date of  delivery  of the  Conversion
          Notice,  and  cash  for  fractional  shares,  of  Common  Stock on the
          foregoing basis. The Series D Preferred Shares shall be deemed to have
          been converted,  and the person converting the same to have become the
          holder of record of Common  Stock,  for all purposes as of the date of
          delivery of the Conversion Notice.

               (f) The Company  shall,  so long as any of the Series D Preferred
          Shares  are  outstanding,  reserve  and  keep  available  out  of  its
          authorized  and  unissued  Common  Stock,  solely  for the  purpose of
          effecting the conversion of the Series D Preferred Shares, such number
          of shares of Common Stock as shall from time to time be  sufficient to
          effect the  conversion  of all of the Series D  Preferred  Shares then
          outstanding.

               (g) The Company  shall pay any and all taxes which may be imposed
          upon it with respect to the issuance and delivery of Common Stock upon
          the  conversion of the Series D Preferred  Shares as herein  provided.
          The Company  shall not be required in any event to pay any transfer or
          other taxes by reason of the  issuance  of such Common  Stock in names
          other than those in which the Series D  Preferred  Shares  surrendered
          for conversion are  registered on the Company's  records,  and no such
          conversion  or issuance of Common Stock shall be made unless and until
          the person requesting such issuance has paid to the Company the amount
          of any such tax, or has established to the satisfaction of the Company
          and its transfer agent, if any, that such tax has been paid.

     (3) Voting  Rights.  Holders  of Series D  Preferred  Shares  shall have no
voting rights, except as required by law and by Section 7 hereof.

     (4) Redemption. The Company may, but shall not be obligated to, at any time
subsequent  to ninety  (90) days after the  issuance  of the Series D  Preferred
Shares,  redeem  the whole or any part of the  Series D  Preferred  Shares  then
outstanding  at a redemption  price of $127 per Preferred  Share,  in accordance
with the following redemption procedures:

          (a) In case of  redemption  of only  part of the  Series  D  Preferred
     Shares at any time  outstanding,  the Company shall designate the amount of
     Series D Preferred  Shares so to be redeemed and shall redeem such Series D
     Preferred  Shares  on a pro rata  basis.  Subject  to the  limitations  and
     provisions  herein  contained,  the Board of Directors shall have the power
     and authority to prescribe the terms and conditions upon which the Series D
     Preferred Shares shall be redeemed from time to time.

                                      - 5 -

<PAGE>
          (b) Notice of every  redemption shall be given by mail to every holder
     of record of any Series D Preferred  Shares then to be  redeemed,  at least
     thirty (30), but no more than ninety (90),  days prior to the date fixed as
     the date for the redemption  thereof,  at the respective  addresses of such
     holders  as the  same  shall  appear  on the  stock  transfer  books of the
     Company. The notice shall state that the Series D Preferred Shares shall be
     redeemed by the Company at the redemption price specified  above,  upon the
     surrender  for  cancellation,  at the time  and  place  designated  in such
     notice,  of the certificates  representing the Series D Preferred Shares to
     be redeemed,  properly  endorsed in blank for transfer,  or  accompanied by
     proper  instruments  of assignment and transfer in blank,  with  signatures
     guaranteed,  and bearing all necessary  transfer tax stamps thereto affixed
     and  cancelled.  On and after the date  specified  in the notice  described
     above, each holder of Series D Preferred Shares called for redemption shall
     be  entitled  to  receive  therefor  the  specified  redemption  price upon
     presentation  and  surrender at the place  designated in such notice of the
     certificates for Series D Preferred Shares called for redemption,  properly
     endorsed in blank for  transfer or  accompanied  by proper  instruments  of
     assignment or transfer in blank,  with signatures  guaranteed,  and bearing
     all necessary transfer tax stamps thereto affixed and cancelled.

          (c) If the Company shall give notice of  redemption as aforesaid  (and
     unless the Company shall fail to pay the  redemption  price of the Series D
     Preferred  Shares presented for redemption in accordance with such notice),
     all Series D Preferred Shares called for redemption shall be deemed to have
     been  redeemed on the date  specified  in such  notice,  whether or not the
     certificates  for such Series D Preferred  Shares shall be surrendered  for
     redemption,  and such  Series D Preferred  Shares so called for  redemption
     shall from and after such date cease to represent  any interest  whatsoever
     in the  Company or its  property,  and the  holders  thereof  shall have no
     rights other than the right to receive such  redemption  price  without any
     interest thereof from and after such date.

     (5) Liquidation,  Dissolution, Winding Up. In the event of any voluntary or
involuntary  liquidation,  dissolution or winding up of the Company, the holders
of the Series D Preferred Shares shall be entitled to receive in cash out of the
assets of the  Company,  whether from capital or from  earnings,  available  for
distribution  to its  stockholders  (the "Preferred  Funds"),  before any amount
shall be paid to the holders of the Common Stock,  an amount equal to the Stated
Value per Series D Preferred  Share,  provided that, if the Preferred  Funds are
insufficient  to pay the full  amount due to the  holders of Series D  Preferred
Shares and holders of shares of other  classes or series of  preferred  stock of
the  Company  that are of equal  rank with the Series D  Preferred  Shares as to
payments  of  Preferred  Funds (the "Pari  Passu  Shares"),  then each holder of
Series D Preferred Shares and Pari Passu

                                      - 6 -

<PAGE>

Shares  shall  receive a  percentage  of the  Preferred  Funds equal to the full
amount of Preferred  Funds  payable to such holder as a  percentage  of the full
amount of Preferred  Funds  payable to all holders of Series D Preferred  Shares
and Pari Passu Shares. The purchase or redemption by the Company of stock of any
class, in any manner  permitted by law, shall not, for the purposes  hereof,  be
regarded as a liquidation, dissolution or winding up of the Company. Neither the
consolidation  nor merger of the Company with or into any other  corporation  or
corporations, nor the sale or transfer by the Company of less than substantially
all  of  its  assets,  shall,  for  the  purposes  hereof,  be  deemed  to  be a
liquidation,  dissolution  or winding up of the  Company.  No holder of Series D
Preferred  Shares shall be entitled to receive any amounts with respect  thereto
upon any  liquidation,  dissolution  or winding up of the Company other than the
amounts provided for herein.

     (6) Preferred  Rank.  All shares of Common Stock shall be of junior rank to
all Series D Preferred  Shares in respect to the preferences as to distributions
and payments upon the liquidation, dissolution or winding up of the Company. The
rights of the shares of Common  Stock  shall be subject to the  preferences  and
relative rights of the Series D Preferred Shares.  The Series D Preferred Shares
shall be of  equal  rank  with the  Company's  Series A  Cumulative  Convertible
Preferred  Stock and the Series B Preferred  Shares in respect of  distributions
and payments  upon the  liquidation,  dissolution  or winding up of the Company.
Notwithstanding the foregoing, the Company may authorize and issue additional or
other  preferred  stock  which is of  equal or  junior  rank  with the  Series D
Preferred Shares in respect of the preferences as to distributions  and payments
upon the  liquidation,  dissolution  or  winding  up of the  Company;  provided,
however,  that for so long as the Series D Preferred  Shares remain  outstanding
the Company  shall not issue any capital stock which is more senior in rank than
the Series D Preferred  Shares in respect of the foregoing  preferences.  In the
event  of the  merger  or  consolidation  of the  Company  with or into  another
corporation, the Series D Preferred Shares shall maintain their relative powers,
designations and preferences provided for herein.

     (7) Vote to Change the Terms of Series D Preferred Shares.  The affirmative
vote at a meeting duly called for such purpose or the written  consent without a
meeting of the holders of not less than two-thirds (2/3) of the then outstanding
Series D Preferred  Shares shall be required to amend,  alter,  change or repeal
any of the  powers,  designations,  preferences  and  rights  of  the  Series  D
Preferred Shares.

                                      - 7 -

<PAGE>

         IN WITNESS  WHEREOF,  the  Company has caused  this  certificate  to be
signed by Peter G. Tombros,  its President,  and John A. Caruso,  its Secretary,
this 28th day of February 1997.

                                                     ENZON, INC.



                                                     By: /S/PETER G. TOMBROS
                                                     -----------------------
                                                              President



                                                     Attest: /S/JOHN A. CARUSO
                                                     -------------------------
                                                               Secretary

                                      - 8 -



                            STOCK EXCHANGE AGREEMENT


         This STOCK  EXCHANGE  AGREEMENT is made and entered into as of February
28, 1997 by and among Enzon, Inc., a Delaware  corporation (the "Company"),  and
the GFL  Performance  Fund Ltd., a corporation  organized  under the laws of the
British Virgin Islands, the holder (the "Series C Stockholder") of the Company's
Series C Convertible  Preferred Stock,  $0.01 par value per share (the "Series C
Preferred Stock").


                                R E C I T A L S:

         WHEREAS,  the Company  desires to induce the Series C Stockholder,  and
the Series C  Stockholder  is willing,  to (i)  exchange  its shares of Series C
Preferred Stock for an equal number of shares of the Company's newly  designated
Series D  Convertible  Preferred  Stock,  $0.01 par value  share (the  "Series D
Convertible  Preferred Stock"),  (ii) immediately convert its shares of Series D
Convertible Preferred Stock into the Company's Common Stock, $0.01 par value per
Share (the "Common  Stock"),  and (iii) agree not to sell or otherwise  transfer
the shares of Common  Stock  issued  upon  conversion  of the Series D Preferred
Stock for a period of twelve (12) months from the date of this agreement without
the prior written consent of the Company.

         NOW THEREFORE, in consideration of the foregoing,  the representations,
warranties  and  agreements of the parties  contained  herein and other good and
valuable  consideration,   the  receipt  and  sufficiency  of  which  is  hereby
acknowledged, the parties hereto agree as follows:

         1.       SHARE EXCHANGE

                  1.1 Exchange.  The Series C Stockholder  does hereby transfer,
assign,  convey  and  deliver  to the  Company  the number of shares of Series C
Preferred Stock set forth opposite that  Stockholder's  name on Schedule 1.1, in
exchange for an equal number of Shares of Series D Preferred Stock. The Series C
Stockholder  has  delivered  to the  Company  the  certificate  or  certificates
representing  such shares of Series C Preferred Stock,  with duly executed stock
powers  endorsed in blank,  and the shares of Series C Preferred Stock delivered
hereunder  shall be cancelled and a new  certificate  or  certificates  shall be
issued and delivered promptly to the Series C Stockholder evidencing that number
of shares of Series D Preferred  Stock equal to the number of shares of Series C
Preferred Stock set forth opposite such Series C Stockholder's  name on Schedule
1.1.

     1.2 Registration Rights Agreement. The parties hereto acknowledge and agree
that the Common Stock issuable upon  conversion of the Series D Preferred  Stock
shall be treated as "Conversion  Shares"  pursuant to that certain  Registration
Rights Agreement (the

<PAGE>


"Registration Rights Agreement"), dated as of March 15, 1996, by and between the
Company and the Buyer (as defined  therein) and that the rights and  obligations
of  the  parties  under  the  Registration  Rights  Agreement  with  respect  to
Conversion Shares (as defined in the Registration  Rights Agreement) will attach
to the shares of Common Stock issuable upon conversion of the Series D Preferred
Stock,  provided,  however,  that  the  obligation  of  the  Company  to  file a
registration  statement with respect to the shares of Common Stock issuable upon
exercise of the Series D Preferred  Stock shall not  commence  until two hundred
ten (210) days from the date hereof.

                  1.3 Securities Purchase Agreement. Sections 2(d), (e), (f) and
(g); 4(b), (c), (h) and (j); and 5 (the "Surviving  Sections") of the Securities
Purchase Agreement (the "Securities Purchase Agreement"),  dated as of March 15,
1996,  by and between the  Company  and the Buyer (as defined  therein)  and the
definitions  of  defined  terms  used  in the  Surviving  Sections  but  defined
elsewhere in the Securities  Purchase  Agreement  shall remain in full force and
effect as if the  shares  of Series D  Preferred  Stock  issued to the  Series C
Stockholder  hereunder were issued and sold to the Series C Stockholder pursuant
to the  Securities  Purchase  Agreement  at the  time  the  shares  of  Series C
Preferred  Stock  purchased by the Series C Stockholder  thereunder were issued.
Except as provided in the preceding sentence,  the Securities Purchase Agreement
shall be deemed to be terminated and the provisions  thereof to be null and void
and the  rights  of the  Series  C  Stockholder  with  respect  to the  Series D
Preferred Stock and Warrants (as defined in the Securities  Purchase  Agreement)
issued to the Series C  Stockholder  shall be governed by and subject to (A) the
Certificate of Designations (the "Certificate of Designations")  relating to the
Series D Preferred  Stock,  a copy of which is attached  hereto as Exhibit A and
made a part hereof,  (B) the Registration  Rights Agreement,  a copy of which is
attached  hereto as Exhibit B and made a part  hereof,  and (C) the  Amended and
Restated  Warrant,  of even  date  herewith,  by the  Company  in  favor  of GFL
Performance Fund Ltd., a copy of which is attached hereto as Exhibit C.

                  1.4  Lock-up.  The Series C  Stockholder  agrees that from the
date  hereof and  continuing  for a period of twelve (12)  months,  it will not,
without the Company's prior written  consent,  offer,  sell or contract to sell,
directly or indirectly,  any shares of the Company's Common Stock received by it
upon conversion of the Series D Preferred Stock.

         2.       REPRESENTATIONS AND WARRANTIES OF THE COMPANY

                  The  Company   represents   and   warrants  to  the  Series  C
Stockholder as follows:

     2.1  Existence  and Power.  The  Company is  validly  existing  and in good
standing under the laws of its state of incorporation.  The Company has the full
corporate  power and authority to enter into and perform this Agreement and each
other  instrument  it is  executing  and  delivering  in  connection  with  this
Agreement (collectively,  the "Transaction Documents"). The Company has the full
corporate power and authority to carry on its business as now conducted,  and to
own, lease and operate its properties as it now does. The

                                      - 2 -

<PAGE>

Company  is  qualified  to  do  business  as  a  foreign   corporation  in  each
jurisdiction in which it is required to be qualified.

                  2.2 Authorization.  The execution, delivery and performance of
each of the  Transaction  Documents  have been duly  authorized by all necessary
action, and each of the Transaction  Documents constitutes the valid and binding
obligation of the Company enforceable against the Company in accordance with its
terms,  except  to the  extent  enforceability  may be  limited  by  bankruptcy,
insolvency,  reorganization,  moratorium  or other  similar laws  affecting  the
enforcement of creditors' rights in general and subject to general principles of
equity  (regardless of whether  enforceability  is considered in a proceeding in
equity or at law).

                  2.3 Consents of Third  Parties.  The  execution,  delivery and
performance  of each of the  Transaction  Documents  by the Company will not (a)
violate or conflict  with the  certificate  of  incorporation  or by-laws of the
Company; (b) conflict with, or result in the breach, termination or acceleration
of, or constitute a default  under,  any lease,  mortgage,  license,  agreement,
commitment or other instrument to which the Company is a party or by which it or
any of its  properties  are  bound;  (c)  constitute  a  violation  of any  law,
regulation,  order,  writ,  judgment,  injunction  or decree  applicable  to the
Company or any of the Company's properties or require any governmental  consent,
registration  or  approval;  or (d) result in the  creation of any lien upon the
properties or assets of the Company.

                  2.4 Litigation.  There is no judicial or administrative action
or proceeding pending or, to the best knowledge of the Company, threatened, nor,
to the best knowledge of the Company,  is there any  governmental  investigation
pending or  threatened,  that  questions the validity of any of the  Transaction
Documents or any action taken or to be taken by the Company in  connection  with
any of the Transaction Documents.

                  2.5 Validity of Shares. The shares of Series D Preferred Stock
issued by the Company in  exchange  for Series C  Preferred  Stock,  are validly
issued, fully paid and non-assessable.

         3.       REPRESENTATIONS AND WARRANTIES OF THE Series C Stockholder.

                  The Series C Stockholder hereby represents and warrants to the
Company as follows:

                  3.1  Existence  and Power.  That the Series C  Stockholder  is
validly  existing and in good standing under the law of the  jurisdiction of its
organization and has the full power and authority to enter into and perform this
Agreement.

          3.2  Authorization.  The execution,  delivery and  performance of this
     Agreement  has been  duly  authorized  by all  necessary  action,  and this
     Agreement  constitutes  the valid and  binding  obligation  of the Series C
     Stockholder enforceable against it in

                                      - 3 -

<PAGE>
          accordance with its terms, except to the extent  enforceability may be
     limited by  bankruptcy,  insolvency,  reorganization,  moratorium  or other
     similar laws affecting the enforcement of creditors'  rights in general and
     subject   to  general   principles   of  equity   (regardless   of  whether
     enforceability is considered in a proceeding in equity or at law).

                  3.3 Consents of Third  Parties.  The  execution,  delivery and
performance   this  Agreement  will  not:  (a)  violate  or  conflict  with  its
partnership agreement,  certificate of incorporation or by-laws or other similar
organizational  documents of the Series C  Stockholder;  (b) conflict  with,  or
result in the breach,  termination or  acceleration  of, or constitute a default
under, any lease, mortgage, license,  agreement,  commitment or other instrument
to which it is a party or by which it or any of its properties are bound; or (c)
constitute a violation of any law, regulation, order, writ, judgment, injunction
or decree  applicable to it or any of its properties or require any governmental
consent, registration or approval.

                  3.4 Litigation.  There is no judicial or administrative action
or  proceeding  pending or, to the best  knowledge of the Series C  Stockholder,
threatened, nor, to the best knowledge of the Series C Stockholder, is there any
governmental investigation pending or threatened, that questions the validity of
this Agreement or any action taken or to be taken by it in connection  with this
Agreement.

                  3.5  Investment.  The Series C  Stockholder  is an  accredited
investor  (within the meaning of the rules and regulations  under the Securities
Act of 1933,  as amended)  and will be  acquiring  Series D Preferred  Stock for
investment  and not with a view to  distribution  in violation of the Securities
Act.

                  3.6 Brokers.  No agreement,  arrangement or understanding with
any broker or finder in connection  with the  transactions  contemplated by this
Agreement has been entered into by that Series C Stockholder.

                  3.7  Ownership.  That each Series C Stockholder  is the record
and  beneficial  owner of the  shares  of  Series C  Preferred  Stock  set forth
opposite that Series C Stockholder's name on Schedule 1.1, free and clear of all
liens, claims and encumbrances of any kind.

         4.       ADDITIONAL AGREEMENTS.

                  4.1 Indemnification.  The Company, on one hand, and the Series
C Stockholder, on the other hand, agree to indemnify and hold harmless the other
party from and against any and all damage,  loss,  liability,  claim, or expense
(including  reasonable  attorney's  fees) incurred by such other party resulting
from,  or which exists or arises due to (i) any  inaccuracy,  breach or omission
of, from, or in, the  representations  and warranties of such party contained in
this  Agreement,  or (ii) the  nonfulfillment  of any agreement or obligation of
such party under this Agreement.


                                      - 4 -

<PAGE>

                  4.2 Further  Acknowledgement.  The Series C Stockholder hereby
authorizes the  cancellation of the Series C Preferred Stock and the issuance of
Series D Preferred Stock to such holder.  The Series C Stockholder  acknowledges
and  agrees  that,  except as  provided  herein,  upon the  consummation  of the
transactions contemplated by this Agreement such Series C Stockholder shall have
no rights as a Series C Stockholder and further, that this Agreement constitutes
a  settlement  and  relinquishment  of its  rights as a holder  of the  Series C
Preferred  Stock,  including  but not  limited  to, the  conversion  rights with
respect to the Series C Preferred  Stock.  Accordingly,  in consideration of the
agreements  made by the  Company  hereunder,  the  Series C  Stockholder  hereby
releases and  discharges the Company,  and its successors and assigns,  from any
and all claims,  demands,  rights or liabilities  which the Series C Stockholder
ever had, now has or may have in the future, by reason of, arising out of, or in
any way  connected  with the  Series C  Stockholder's  status as a holder of the
Series C Preferred Stock.

         5.       GENERAL PROVISIONS.

                  The parties further covenant and agree as follows:

          5.1  Amendments.  This  Agreement  may  be  amended,  supplemented  or
     interpreted only by written instrument duly executed by each of the parties
     hereto.

                  5.2 Contents of  Agreement,  Parties in Interest,  Assignment.
This Agreement sets forth the entire  understanding  of the parties with respect
to the subject matter hereof. Any previous agreements or understandings  between
the parties  regarding the subject  matter hereof are merged into and superseded
by this Agreement in accordance with its terms. All representations, warranties,
terms and  conditions of this  Agreement  shall be binding upon and inure to the
benefit of and be enforceable by the respective  heirs,  legal  representatives,
successors and permitted assigns of the parties hereto.

                  5.3  Severability.  In the  event  that any one or more of the
provisions   contained  in  this   Agreement   shall  be  invalid,   illegal  or
unenforceable  in any  respect  for  any  reason,  the  validity,  legality  and
enforceability of any such provision in every other respect and of the remaining
provisions of this Agreement shall not be in any way impaired.

          5.4 Headings. The headings of the Sections and the subsections of this
     Agreement  are inserted  for  convenience  of reference  only and shall not
     constitute a part hereof.

                  5.5  Instruments  of Further  Assurance.  Each of the  parties
hereto agrees,  upon the request of any of the other party hereto,  from time to
time  to  executive  and  deliver  to such  other  party  or  parties  all  such
instruments  and  documents  of  further  assurance  or  otherwise  as  shall be
reasonable under the  circumstances,  and to do any and all such acts and things
as may  reasonably be required to carry out the  obligations  of such  requested
party hereunder.

                                      - 5 -

<PAGE>
                  5.6 Specific Performance, Etc. Each of the parties hereto will
be entitled to specific performance of its rights under this Agreement.  Each of
the  parties  hereto  agrees  that a  breach  of any of the  provisions  of this
Agreement will cause  irreparable  injury to the nonbreaching  party,  that such
nonbreaching party have no adequate remedy at law in respect of such breach and,
as a  consequence,  that each and every  provision  contained in this  Agreement
shall be specifically enforceable against all parties hereto.

                  5.7  Governing  Law;  Jurisdiction.  This  Agreement  shall be
governed,  construed  and enforced in  accordance  with the internal laws of the
State of  Delaware,  excluding  any  choice of law rules  which may  direct  the
application of the laws of another jurisdiction.

                  5.8   Counterparts.   This   Agreement   may  be  executed  in
counterparts,  each of which shall be considered  an original,  but all of which
together shall constitute the same instrument.

         IN WITNESS  WHEREOF,  this  Agreement  has been executed by the parties
hereto as of the day and year first above written.


                                                     ENZON, INC.


                                                     By:  /S/KENNETH J. ZUERBLIS
                                                     ---------------------------
                                                       Name: Kenneth J. Zuerblis
                                                Its: Vice President, Finance and
                                                         Chief Financial Officer


                                                     GFL PERFORMANCE FUND LTD.


                                                     By:  /S/HANS FREDERIC HEYE
                                                     --------------------------
                                                     Name: Hans Frederic Heye
                                                     Its:  Director
                                              Address: GFL Performance Fund Ltd.
                                                            c/o Clearwater Funds
                                                             611 Druid Road East
                                                                       Suite 200
                                                       Clearwater, Florida 34616

                                                                   Administrator
                                            Curacao International Trust Co. N.V.
                                                                Kaya Flamboyan 9
                                                                    P.O. Box 812
                                                    Curacao, Netherland Antilles

                                      - 6 -


                  AGREEMENT REGARDING REGISTRATION RIGHTS UNDER
                          REGISTRATION RIGHTS AGREEMENT

Enzon, Inc.
20 Kingsbridge Road
Piscataway, NJ 08854

Dear Sir or Madam:

                  Reference is hereby made to the Registration  Rights Agreement
(the  "Registration  Rights Agreement") dated March 15, 1996 by and among Enzon,
Inc. and the security holders named on the signature page thereto, including the
undersigned.

                  The  undersigned  understand  that  in  arranging  for (i) the
exchange of the Company's Series C Convertible  Preferred Stock (the "Series C")
and warrants to purchase  common stock,  par value $.01 (the "Common  Stock") of
the Company  issued in connection  with the issuance of the Series C, for shares
of Series D  Convertible  Preferred  Stock (the  "Series D") and  warrants  (the
"Series D Warrants")  issued in connection with the issuance of the Series D and
(ii) the transfer from GFL Advantage Fund Ltd. to Clearwater  Fund IV LLC of the
warrants (the "Series B Warrants") to purchase Common Stock issued in connection
with the private  placement  of the  Company's  Series B  Convertible  Preferred
Stock,  the Company  will be required to (i) file a new  registration  statement
(the "New Registration  Statement") with respect to outstanding shares of Common
Stock,  shares of Common Stock issuable on conversion of the Series D, shares of
Common  Stock  issuable  on  exercise  of the Series D Warrants  (the  "Series D
Shares")  and (ii) with  respect to the shares of Common  Stock  underlying  the
Series B Warrants (the "Warrant  Shares") (A) include the Warrant  Shares in the
New Registration Statement or (B) file a post-effective  amendment or supplement
to the Prospectus  dated May 7, 1996 relating to, inter alia, the Warrant Shares
(the "Amended Registration Statement"). The undersigned further acknowledge that
during  the  period  prior  to the  determination  of the  effectiveness  of the
Registration  Statement by the Securities and Exchange Commission  ("SEC"),  the
SEC  may  comment  on  the   Registration   Statement  or  otherwise  delay  the
effectiveness of the Registration Statement for a period of time.

           Pursuant  to Section 10 of the  Registration  Rights  Agreement,  the
undersigned  hereby  agree (i) to the Company  using its best  efforts to file a
registration  statement with respect to the Series D Shares within 210 days from
the date  hereof,  (ii) to the  Company  using its best  efforts to include  the
Warrant  Shares on the Amended  Registration  Statement or the New  Registration
Statement and to secure the  effectiveness of such  registration  statements and
(iii) that during the period subsequent to the

<PAGE>

filing of and prior to the SEC declaring the Amended  Registration  Statement or
New  Registration  Statement  effective,  the  Company  will be  deemed  in full
compliance with its obligations under the Registration  Rights Agreement and the
undersigned hereby waives any penalties,  remedies or any other rights available
under such agreement  with respect to the matters  covered in sections (i), (ii)
and (iii) of this paragraph and agrees that any such penalties,  remedies or any
other rights will be unavailable.

                  This agreement is limited to the matters described herein.

                  This  consent may be executed in  counterparts,  each of which
shall be considered an original,  but all of which together shall constitute the
same instrument.




Dated:  March 10, 1997

                                                          CLEARWATER FUND IV LLC

                                                             By: /S/HANS F. HEYE
                                                             -------------------
                                      - 2 -


<TABLE> <S> <C>


<ARTICLE>                     5
<LEGEND>
This schedule contains summary financial  information  extracted from the Enzon,
Inc. and Subsidiaries  Consolidated Condensed Balance Sheet as of March 31, 1997
and the  Consolidated  Condensed  Statement of Operations for the three and nine
months  ended March 31, 1997 and is  qualified  in its  entirety by reference to
such financial statements.                                                      
</LEGEND>
       
<S>                                   <C>                        <C>
<PERIOD-TYPE>                               3-MOS                     9-MOS
<FISCAL-YEAR-END>                     JUN-30-1996               JUN-30-1996
<PERIOD-END>                          MAR-31-1997               MAR-31-1997
<CASH>                                 $9,596,973                $9,596,973
<SECURITIES>                                    0                         0
<RECEIVABLES>                           2,326,397                 2,326,397
<ALLOWANCES>                                    0                         0
<INVENTORY>                               891,275                   891,275
<CURRENT-ASSETS>                       12,937,693                12,937,693
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                           0                         0
                                 1,090                     1,090
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<SALES>                                 2,350,113                 8,624,679
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<CGS>                                   1,070,822                 3,051,136
<TOTAL-COSTS>                           4,500,101                13,619,861
<OTHER-EXPENSES>                                0                         0
<LOSS-PROVISION>                                0                         0
<INTEREST-EXPENSE>                          2,613                    14,213
<INCOME-PRETAX>                       (1,991,789)               (3,421,248)
<INCOME-TAX>                                    0                         0
<INCOME-CONTINUING>                   (1,991,789)               (3,421,248)
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<CHANGES>                                       0                         0
<NET-INCOME>                          (1,991,789)               (3,421,248)
<EPS-PRIMARY>                              (0.07)                    (0.13)
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