EXHIBIT 10(cc)

                          AGREEMENT FOR LICENSE BETWEEN
                     YALE UNIVERSITY AND ENZO BIOCHEM, INC.

     THIS AGREEMENT entered into as of the fourth, (4th) day of December, 1981,
by and between Yale University (hereinafter called Yale) a corporation organized
and existing under and by virtue of a charter granted by the General Assembly of
the Colony and State of Connecticut and located in New Haven, Connecticut 06510,
and Enzo Biochem, Inc. (hereinafter called Enzo), a corporation of the State of
New York having its principal office at 325 Hudson Street, New York, New York
10013;

                                WITNESSETH THAT:

     IN CONSIDERATION OF the mutual promises herein contained THE PARTIES HAVE
AGREED AND DO AGREE AS FOLLOWS:

I.   LICENSE GRANT

     A. Yale hereby grants to Enzo, upon and subject to all the terms and
conditions of this agreement, an EXCLUSIVE LICENSE of limited term as defined by
Article II B, to make, use and sell the invention covered by the LICENSED
PATENTS as defined by Article III, in the countries where the LICENSED PATENTS
are effective or applications are pending.

     B. Yale grants to Enzo a NONEXCLUSIVE LICENSE for a residual term as
defined by Article II C to make, use and sell the invention covered by the
LICENSED PATENTS as defined by Article III in the countries where the LICENSED
PATENTS are effective or applications are pending.

  

     C. Yale further grants to Enzo the right to sublicense third parties under
terms and conditions no greater than   those acquired by Enzo and provided that
the terms and provisions of the following clauses of this agreement are met
where applicable.

     D. All rights granted by Yale to Enzo under this agreement are subject to
any rights required to be granted to the Government and any rights reserved or
determined by the Government thereunder.

II.  TERMS OF AGREEMENT

     A. The terms, conditions and obligations of this agreement become effective
as of the date of signing.

     B. The term of the EXCLUSIVE LICENSE granted under this agreement shall be
for ten (10) years commencing with the effective date pursuant to Article XXIII
of this agreement or for a shorter period as may be determined or approved by
the Federal Government or any agency thereof.

     C. The term of the NONEXCLUSIVE LICENSE granted under this agreement shall
be for the remaining years of the life of each patent, domestic or foreign, of
the LICENSED PATENTS exceeding the EXCLUSIVE LICENSE term.

III. LICENSED PATENTS

     As used in the agreement, the phrase "LICENSED PATENTS" shall mean and
include:

     A. United States Patent Application Serial No. 255,223, entitled "Modified
Nucleotides and Methods of


                                        2

  

Preparing and Using Same," filed April 17, 1981, by David C. Ward, Pennina R.
Langer and Alexander A. Waldrop III (hereinafter called the Ward application);

     B. Any divisional, continuation or substitute United States patent
application which shall be based on the Ward application;

     C. Any patents which shall issue on any of the above- described patent
applications, and any reissues and extensions thereof;

     D. And, foreign patents or patent applications corresponding to each of the
above-described patent applications.

IV.  PATENT PROSECUTION

     A. If not already accomplished at the time of execution of this agreement,
the patent applications included within the LICENSED PATENTS shall be prepared,
filed and prosecuted to issuance, grant or final disposition by Enzo at its own
cost and expense.

     B. Enzo shall prepare and file foreign patent applications corresponding to
the LICENSED PATENTS within the Paris Convention time period in those countries
where valid patent protection is obtainable, including at least the Common
Market European Countries, Japan and Canada, and in other foreign countries
mutually agreeable to Yale and Enzo. Enzo shall prosecute these applications,
and any renewals or extensions thereof at its own cost and expense.


                                        3

  

     C. Any taxes, annuities, working fees, maintenance fees, renewal and
extension charges with respect to each patent application and patent subject to
this agreement shall be punctually paid by Enzo. A mutually acceptable patent
counsel for these purposes shall be engaged by Enzo.

V.   ROYALTIES

     A. During the EXCLUSIVE LICENSE term as defined by Article II B, Enzo shall
pay to Yale a royalty of:

          1. * percent of all domestic or foreign sales covered by the LICENSED
PATENTS in each country in which the invention is manufactured, sold or used
and,

          2. * percent of the unit price of diagnostic kits applied to the
diagnosis of human or animal disorders and in which the invention of the
LICENSED PATENTS is a component part.

          3. * percent of the unit price of research kits (e.g., nick
translation, cDNA kits) in which the invention of the LICENSED PATENTS is a
component part.

     B. After the expiration of the EXCLUSIVE LICENSE term and during the
NONEXCLUSIVE LICENSE term as defined by Article II, Enzo shall pay a royalty of:

          1. * percent of all domestic and foreign sales covered by the LICENSED
PATENTS which includes the unit price of diagnostic kits applied to the
diagnosis of human

- ----------
* The information omitted is confidential and has been filed separately with the
  Commission pursuant to Rule 24b-2.


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or animal disorders and in which the invention of the LICENSED PATENTS is a
component part, in each country in which the invention is manufactured, sold or
used.

          2. * percent of the unit price of research kits (e.g., nick
translation, cDNA kits) in which the invention of the LICENSED PATENTS is a
component part.

     C. As used in this agreement, "sales" shall mean Enzo's billings for
products, processes, kits, etc. covered by the LICENSED PATENTS, less the sum of
the following:

          1. Sales and/or use taxes directly imposed upon and with particular
          reference to particular sales of apparatus;

          2. Outbound freight separately charged or prepaid;

          3. Special packing or crating separately charged;

          4. Refunds paid for sales previously credited.

     D. In countries where no patent application is filed and Enzo licenses
others to practice the invention of the LICENSED PATENTS, Enzo shall pay to Yale
a royalty of *

- ----------
* The information omitted is confidential and has been filed separately with the
  Commission pursuant to Rule 24b-2.


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VI.  PAYMENTS AND REPORTS

     A. On or before the last business day of January, April, July and October
of each year of this agreement, Enzo shall submit to Yale a written report
stating:

          1. The billings by Enzo issued during the preceding calendar quarter
          for sales covered by the LICENSED PATENTS;

          2. Any deductions therefrom under Article V B 1-4;

          3. a) A calculation of the minimum payment due as defined by Article
          VII; b) a calculation of the amount of royalty due; and a payment to
          Yale each quarter of an amount equal to the greater of the aforesaid
          calculations a) or b).

     B. Enzo shall maintain at its principal office usual books of account and
records showing its actions under this agreement. Such books and records shall
be open to inspection and copying, during usual business hours, by an
independent certified public accountant to whom Enzo has no reasonable
objection, for two (2) years after the calendar quarter to which they pertain,
for the purposes of verifying the accuracy of the royalties paid by Enzo under
this agreement.

VII. MINIMUM PAYMENTS

     A. Enzo agrees to pay to Yale the following annual minimum payments for the
licenses herein granted under the LICENSED PATENTS. The term of the minimum
payments schedule


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commences with the Effective Date of this Agreement of Article XXIII January 1,
1982 and payments shall be made quarterly whether or not any annual sales of the
invention covered by the LICENSED PATENTS have been made:


          First year     $ 5,000.00          Sixth year    $100,000.00
          Second year    $10,000.00          Seventh year  $200,000.00
          Third year     $15,000.00          Eighth year   $300,000.00
          Fourth year    $20,000.00          Ninth year    $400,000.00
          Fifth year     $25,000.00          Tenth year    $500,000.00

     B. Each quarter one-fourth of the annual minimum payment shall become due
and payable in accordance with the provision of Article VI. Royalty payments due
and payable during each quarter shall be credited against any minimum payment
due for the particular quarter.

     C. Enzo may terminate the EXCLUSIVE LICENSE granted under this Agreement at
the end of the sixth year without incurring future liabilities under the minimum
payment provisions of this Agreement. Termination under this paragraph must be
made in writing by Enzo to Yale during the ninety (90) days immediately
proceeding the conclusion of the sixth anniversary year of this Agreement. If
this Agreement is terminated by Enzo under this paragraph, all royalties accrued
under this agreement shall immediately become due. Yale may immediately seek
another licensee to succeed Enzo.

     D. In the event that Enzo fails to pay fully and promptly any of the
minimum payments or the royalties due under this agreement, Enzo shall be in
material breach of the agreement. If after notice thereof to Enzo by Yale, Enzo
fails to cure its failure to pay within thirty (30) days of notice, Yale may by
ten (10) days notice to Enzo terminate this agreement. Upon such termination for
failure to pay, the full 

                                        7

  

amount of minimum payments shall immediately become due and payable. Upon
payment by Enzo of the unpaid minimum payments, Yale will grant to Enzo a
nonexclusive license to the LICENSED PATENTS without the right to sublicense
others. Payment of royalties under such nonexclusive license shall be off-set by
the amount paid under the termination minimum payment provision.

VIII. TERM OF PAYMENTS

     A. Royalties due under Article VI and minimum payments due under Article
VII shall be payable as long as the Ward application or any division,
continuation, reissue or extension which is the subject of the LICENSED PATENTS,
remains pending in the appropriate countries wherein the royalty was incurred.
Upon said application's issuance as a patent, the royalty shall be payable for
the term of the patent.

     B. In the event that the patent lapses or if all of its claims are declared
invalid by a court of competent jurisdiction through no fault or cause of Enzo,
the obligation to pay the patent royalty for that patent shall terminate but the
Agreement shall remain in effect as to the remaining applications or patents. In
the event that the patent lapses, terminates or all of its claims are declared
invalid through fault or cause by Enzo then as to Enzo its obligations under
this agreement remain in effect and Yale does not waive rights to sue for any
wrongful acts of Enzo. 

                                        8

  

IX.  BEST EFFORTS

     A. For the license granted herein, Enzo shall employ its best efforts to
perfect and market the invention. Best efforts shall be judged by Yale using an
objective standard and the reports and records provided by Enzo as well as other
resources and literature available to or developable by Yale. Should there be
disagreement as to the use of best efforts, a mutually acceptable impartial
third party shall be appointed who shall objectively judge the efforts of Enzo.
Said party shall have suitable scientific and business training in the field or
fields to which the invention applies.


     B. Marketing shall include sales, offers for sale, sales development,
technical consultation pursuant to sales, manufacture, production or processing
pursuant to the invention and sale or possible sale thereof, detailing to
suitable buyers, advertisement, publication of technical reports, sponsorship of
scientific meetings pursuant to or directed to the invention, and further
activities of similar types.

     C. Yale on its part shall employ its best efforts to obtain for Enzo a
ten-year exclusive license under this Agreement.

X.   RESEARCH AND DEVELOPMENT

     A. For the licenses granted herein, Enzo shall furthermore plan, initiate
and maintain research and development efforts related to the invention covered
by the LICENSED PATENTS, which are directed to commercial application of said
invention. Such commercial applications include but are not limited to use of
the invention for analytic or investigative purposes in hospitals and other
health institutions, production of useful and



                                        9

  

valuable products from "DNA" based tissue or cells, detection and analysis of
human pathological conditions and disease and other similar uses.

     B. Pursuant to this effort, Enzo shall spend a minimum of $300,000.00
annually for each of the first three years of this agreement, to conduct
research and development of new and improved diagnostic procedures in which the
sensitivity for detection and/or quantification of genetic material from
microbial or multicellular organisms is increased. Payments made by Enzo under
this Article X for research and development during the first year of this
Agreement in excess of $300,000 shall be credited to the second year and,
payments made during the first and second years in excess of $600,000 shall be
credited to the third year. It is recognized that ENZO, prior to the signing of
this Agreement, has made expenditures for research and development and a credit
of $150,000 for this effort shall be applied against the $300,000 obligation of
the third year.

          1. As a part of this minimum expense, Enzo shall employ the following
          minimum personnel, who shall devote their full efforts and time to
          this work:

               a. An Organic Chemist trained in suitable fields of research and
               having a Ph.D. degree or its equivalent;

               b. An Immunologist trained in suitable fields of research and
               having an M.D. degree


                                       10

  

               or a Ph.D. degree or the equivalent thereof; and

               c. A Molecular Biologist trained in suitable fields of research
               and having a Ph.D. degree or the equivalent thereof.

          2. As a further part of this minimum expense, Enzo shall purchase or
          rent the appropriate laboratory and/or clinical equipment, computer
          capacity and other materials appropriate for the work required by the
          foregoing personnel.

     C. A written report describing the development efforts shall be given
annually by Enzo to Yale. An annual audit of the expenditures made in
conjunction with the development efforts including an audit of the minimum
required expenditures shall be made at Yale's expense by an independent,
mutually acceptable auditor or accountant and the audit shall be reported to
Yale. Material produced by Enzo to Yale under this Agreement which has been
marked "confidential" and contains confidential or proprietary information of
Enzo shall not be disclosed by Yale without first obtaining from Enzo written
approval.

     D. Failure to perform substantially the provisions of this article or to
spend the minimum amount for research and development herein set forth, shall
constitute a material breach by Enzo.


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XI.  SUBLICENSES

     The right to sublicense granted by Yale to Enzo shall be exclusive,
coterminable and transferable with this agreement and the license granted under
it. Enzo may grant one or more sublicenses under the LICENSED PATENTS which
shall be treated according to the terms and provisions hereunder. In the event
that the same royalty schedule is applied by Enzo to its sublicense agreement as
is herein applied, the royalty payment due from Enzo to Yale shall include the
sales of Enzo's sublicensee or sublicensees. In the event that a different
royalty schedule is applied by Enzo to its sublicense agreement, Yale shall
receive an amount of the royalties paid by the sublicensee or sublicensees to
Enzo as if Enzo had manufactured and sold the products.

XII. TERMINATION

     This agreement and the license granted under it may be terminated:

     A. By Yale, upon thirty (30) days notice to Enzo, for Enzo's material
breach of the agreement and Enzo's failure to cure in accordance with Article
XIII B.

     B. At any time, by Enzo, after the sixth anniversary of this agreement and
upon sixty (60) days notice to Yale and upon payment of the minimum payments
defined in Article VII.

     C. Should Enzo commit any act of bankruptcy, become insolvent, file a
petition under any bankruptcy or insolvency act or have any such petition filed
against it, or offer any general composition to its creditors, without notice to
Yale and because of the happening of such act, event or offer;

     D. Upon any termination of this agreement and any license granted under it,
Enzo shall have the right for one year


                                       12

  

to dispose of all products of the invention or substantially completed products
thereof then on hand which would bear royalty under this agreement, and to
complete all orders for such products of the invention then on hand, and
royalties shall be paid with respect to such products of the invention as though
this agreement had not terminated;

     E. Upon any termination of this agreement all sublicensees granted by Enzo
under it shall terminate simultaneously, subject nevertheless to Article XII D.

     F. Termination of this agreement shall not terminate Enzo's obligation to
pay all royalties which shall have been accrued hereunder.

     G. It is understood and agreed that should Yale for any reason grant a
license having a more favorable royalty rate than that charged herein, Yale will
give to Enzo the benefit of such more favorable rate from and after the date of
its establishment.

XIII. BREACH, CURE

     A. In addition to the applicable legal standards, Enzo shall be in material
breach of this agreement for the following reasons:

          1. Failure to use best efforts pursuant to Article IX;

          2. Failure to pay royalties or minimum payments pursuant to Articles V
          and VII;

          3. Breach pursuant to Article X;


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               4. Failure to prosecute reasonably the U.S. and foreign patent
               applications which are the subject of the LICENSED PATENTS, such
               failure including failure to appoint adequate mutually acceptable
               counsel, failure to pay all fees and monies due, failure to pay
               maintenance taxes, failure to follow advice of counsel and
               failure to meet prosecution deadlines after being so notified by
               counsel. Such failure shall not include failure caused by Yale;
               and

               5. Failure to pay patent taxes.

     Termination of this agreement by Enzo or by any act of Enzo shall not
terminate Enzo's obligation to pay any remaining minimum payments under Article
VII.

     B. Enzo shall have the right to cure its material breach; the cure shall be
effected within a reasonable time or within the specific time period set forth
for breach pursuant to Article VII C and in no event later than sixty (60) days
after notice of breach given by Yale. If complete cure cannot be rendered, Enzo
shall have the right to make a substantial cure using its best efforts as judged
according to Article IX A.

XIV. INFRINGEMENT, PATENT MARKINGS

     A. Enzo shall notify Yale of the infringement by a third party of any claim
of any of the LICENSED PATENTS, and Enzo shall proceed to take steps to end such
infringement. Enzo shall


                                       14

  

initiate all legal actions and shall in consultation with Yale select counsel
mutually acceptable and prosecute such actions.

     B. Enzo shall pay the first $100,000 in legal fees and disbursements
pursuant to legal action taken in regard to infringement.

     The remainder of the legal fees and disbursements shall be paid three
quarters by Enzo, one quarter by Yale but in no event shall Yale's payment
exceed the amount of royalties due or minimum payment due from Enzo to Yale
whichever is greater.
                           
     C. Any recovery awarded for patent infringement shall first be used to
reimburse Enzo and Yale for legal fees, disbursements and costs incurred
pursuant to XIV B. Excess recovery over reimbursement shall be * between Yale
and Enzo.

     D. Enzo agrees, and agrees to require its sublicensees, to mark all
products of the invention manufactured under this agreement and the license
granted under it, and under any sublicense granted by it hereunder, in
accordance with the pertinent local patent law.

     E. Any actions brought by third parties against Enzo for products or
processes made, used or sold by Enzo under this agreement are the sole
responsibility of Enzo and do not terminate Enzo's obligations under this
agreement.



                                       15

  

XV.  TITLE, OWNERSHIP

     A. Ownership and legal title to all inventions made by Yale or its
employees with funds not provided by Enzo and covered by the LICENSED PATENTS,
and ownership and legal title to the corresponding domestic and foreign patent
applications and the prospective patents which may issue, shall remain with
Yale.

     B. Ownership and legal title to all inventions made by Enzo or its
employees which are related to the field of art covered by the LICENSED PATENTS
and made pursuant to Enzo's further research and development, and ownership and
legal title to the corresponding domestic and foreign patent applications and
prospective patents which may issue, shall remain with Enzo. Yale shall have a
nonexclusive, royalty free license to make and use said inventions and a
nonexclusive, royalty free license under said patent applications and
prospective patents.

     C. Ownership and legal title to all inventions, patent applications and
prospective patents which may issue and which are sponsored or are made jointly
by Enzo and Yale or their employees and are related to the field of art covered
by the LICENSED PATENTS and made pursuant to Yale's and Enzo's further research
efforts, shall remain with Yale. Enzo shall have a limited EXCLUSIVE LICENSE for
a term defined in Article II B and a residual NONEXCLUSIVE LICENSE for the life
of the patent Article II C to make, use and sell embodiments of said inventions.
The filing and prosecution of said patent



                                       16

  

applications and prospective patents, which shall conform in all respects to the
terms of this agreement.

XVI. NOTICE

     Any notice which is required to be or may be given under this agreement
shall be deemed duly given if given in writing, and dispatched by prepaid first
class registered or certified mail addressed to the party notified at its
address stated in the preamble of this agreement. Each party reserves the right
to change that address from time to time by notice so given.

XVII. ASSIGNABILITY

     This agreement and the license granted under it may be assigned by Enzo
with substantially all its related business, or to any firm or corporation
directly or indirectly controlling, controlled by, or under common control with
Enzo. Enzo shall promptly advise Yale of any such assignment.

XVIII. WARRANTY

     Nothing in this agreement shall be construed as a warranty or
representation by either party as to the validity of any prospective, domestic
or foreign patent which may issue pursuant to the LICENSED PATENTS covering the
invention. Further, nothing in this agreement shall be construed as a warranty
or representation by either party that anything made, used, sold or otherwise
disposed of under any license granted under this agreement is or will be free
from infringement of domestic or foreign patents of third parties.


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XIX. PROHIBITION AGAINST USE OF YALE NAME

     The use of the name Yale, Yale University, or Yale Medical School in any
form for public distribution is prohibited unless written approval is first
obtained from an officer of the University or Dean of the Medical School.

XX.  COMPLIANCE WITH GOVERNMENTAL OBLIGATIONS

     A. Notwithstanding any provisions in this agreement, Yale disclaims any
obligations or liabilities arising under the license provisions if Enzo is
charged in a governmental action for not complying with or fails to comply with
governmental regulations to take effective steps to bring the invention to a
point of practical application. Enzo shall bear the entire cost of justifying
and defending any action brought by any governmental agency.

     B. Enzo shall comply with all governmental requests directed to either Yale
or Enzo and to provide all information and assistance necessary to comply with
the government requests. Failure to take necessary action and to comply with
said requests will be a material breach.

     C. Enzo shall insure that research, development, and marketing under this
agreement will comply with all governmental regulations including, but not
limited to, Federal, State, and municipal legislation and that Enzo will hold
Yale harmless for any of its acts or failure to act arising under this
agreement.


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XXI. U.S. GOVERNMENTAL APPROVAL

     This agreement and the licenses herein granted shall be conditioned upon
United States governmental approval of the ten- year EXCLUSIVE LICENSE herein
described or for any other shorter period as determined or approved by the
Federal Government or any agency thereof. Yale shall take all reasonable and
necessary action to secure such approval from the appropriate governmental
agencies such as the National Institute of Health.

XXII. APPLICABLE LAW

     This agreement shall be construed, interpreted and applied in accordance
with the laws of the State of Connecticut.

XXIII. EFFECTIVE DATE

     The effective date for establishing and calculating all rights and
obligations under this Agreement shall be January 1, 1982.

     IN WITNESS WHEREOF, each of the parties has caused this agreement to be
executed in duplicate originals by its duly authorized representative.

                                                 YALE UNIVERSITY


 /s/ D W                                         By /s/  J  Owens
- ---------------------------                        -------------------------
     Acknowledgement                                      Title


                                                 ENZO BIOCHEM, INC.

 /s/                                             By /s/
- ---------------------------                        -------------------------
     Acknowledgement                                      Title


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          AGREEMENT, entered into this 10th day of April, 1986, by and between
Yale University ("Yale"), a corporation organized and existing under and by
virtue of a charter granted by the General Assembly of the Colony and State of
Connecticut and located in New Haven, Connecticut; and Enzo Biochem, Inc.
("Enzo"), a New York corporation having its principal office at 325 Hudson
Street, New York, New York 10013.

                              W I T N E S S E T H :

          WHEREAS, Yale and Enzo, as of December 4, 1981, entered into a License
Agreement relating to the invention covered by U.S. Serial No. 255,223 entitled
"Modified Nucleotides and Methods of Preparing and Using Same" (the "License
Agreement"); and

          WHEREAS, Yale subsequently filed U.S. Patent Application Serial No.
503,298 entitled "Novel Visualization Polymers and their Application to
Diagnostic Medicine" and corresponding foreign patent applications, covering an
invention owned by Yale; and

          WHEREAS, the applicability of provisions of the License Agreement to
the invention described in Application Serial No. 503,298 has been disputed by
Yale and Enzo, and Yale and Enzo desire hereby to resolve such dispute; and

          WHEREAS, this Agreement is entered into in a spirit of compromise and
will not be used in any proceeding to suggest impropriety by either of the
parties or their employees or agents prior to the date hereof; and

  

          WHEREAS, Yale and Enzo desire to modify and amend certain terms and
conditions of the License Agreement;

          NOW THEREFORE, in consideration of the foregoing and of the mutual
promises herein contained, the parties hereto do agree as follows:

          1. The invention described in U.S. Patent Application Serial No.
503,298 and counterpart foreign patent applications, and any divisional,
continuation, or substitute patent applications, and any patents that issue
therefrom, shall be deemed to be a "Licensed Patent" under the License
Agreement.

          2. Promptly following execution hereof, Yale shall cause to be
transferred to patent counsel mutually agreed upon by Yale and Enzo existing
file documents pertaining to U.S. patent application Serial No. 503,298 and to
counterpart foreign applications filed by Yale. Enzo shall assume the
obligation, under Article IV of the License Agreement, at its own expense and
through such mutually agreed upon patent counsel, to prosecute to issuance,
grant or final disposition the foregoing patent applications, including any
divisional, continuation, or substitute patent applications and any reissues and
extensions of any patents issued with respect to such applications. Enzo shall
use its best efforts to furnish or cause to be furnished to Yale for comments in
advance of their filing all documents prepared in connection with the
prosecution and issuance of such patent applications. Upon receipt by patent
counsel of the file documents transferred as descried above in this paragraph 2,
Enzo 

                                        2

  



shall reimburse Yale $50,400 for amounts expended by Yale prior to the date
hereof in preparing and filing such patent applications.

          3. Article IV of the License Agreement shall be and hereby is amended
to add the following Section D:

          "D.  Notwithstanding any other provision of this or any other
               agreement, with respect to any Licensed Patent for which Enzo is
               a non-exclusive licensee, Enzo shall be responsible only for its
               pro-rata share of patent prosecution expenses, taxes, annuities,
               working and maintenance fees, renewal and extension charges,
               based upon the total number of non-exclusive licensees of such
               patent at the time such expenses are incurred."

          4. Subject, in the case of U.S. Patent Application Serial No. 255,223,
to the approval by the U.S. Government of Yale's request for the right to extend
the term of exclusive license, which request Yale shall pursue with its best
efforts, the Exclusive License term defined in Article IIB of the License
Agreement, shall be and hereby is extended to a term of fourteen years. At the
end of the fourteenth year of the term of Exclusive License and if Enzo is then
in compliance with all of the material terms and conditions of the License
Agreement, with an opportunity for curing any breach having been provided, Enzo
shall have the option to further extend the term of the Exclusive License until
the expiration of the life of the first U.S. Patent to issue under U.S. Patent
Application Serial No. 255,223 or if no such patent shall issue, April 17, 2003.



                                        3

  

          5. The schedule set forth in Section A of Article VII "Minimum
Payments" of the License Agreement shall be and hereby is amended to read as
follows:
   
First Year       5,000        Seventh Year                  55,000

Second Year     10,000        Eighth Year                   70,000

Third Year      15,000        Ninth Year                    85,000

Fourth Year     20,000        Tenth Year                   100,000

Fifth Year      25,000        Eleventh year through        200,000
                              the end of the term          per year
                              of Exclusive License
Sixth Year      40,000
    
          Notwithstanding the preceding, there shall be no Minimum Payments
          payable with respect to any period during which the invention
          described in Patent Application U.S. Serial No. 503,298, and any
          foreign patent applications, divisional, continuation or substitute
          patent applications and any patents issued thereon, are the sole
          Licensed Patents for which an Exclusive License is in effect."

          6. Section C of Article VII of the License Agreement shall be and
hereby is amended to read as follows:

                    "Enzo shall have the right to convert the EXCLUSIVE LICENSE
               granted under this Agreement to a NONEXCLUSIVE LICENSE, or to
               terminate this Agreement, at the end of the tenth or fourteenth
               year of this Agreement without incurring subsequent liabilities
               under the minimum payments provision hereof. An election to
               convert or terminate under this Section must be made in writing
               by Enzo to Yale within 90 days preceding the conclusion of the
               year of this Agreement in which the right is exercised. If this
               Agreement is terminated by Enzo under this Section, all royalties
               accrued hereunder shall at once become due, and Yale may
               immediately seek another licensee or licensees to succeed Enzo."

          7. Article XIV of the License Agreement shall be and hereby is amended
to add new Sections F and G as follows:

* The information omitted is confidential and has been filed separately with the
  Commission pursuant to Rule 24b-2.


                                       4

  

               "F.  Should Enzo become a non-exclusive licensee under this
                    Agreement, during such period:

                    (i) Yale shall, in the first instance have the right to
                    bring and prosecute or settle at its expense any suit for
                    patent infringement and shall be entitled to retain any
                    damages collected therefrom; and

                    (ii) Should Yale decline to bring any such suit after notice
                    by Enzo of a substantial infringer then Enzo shall have the
                    right to bring and conduct at its expense a patent
                    infringement suit against such infringer. Enzo shall, in
                    such event, be entitled to retain any damages collected
                    therefrom. A substantial infringer shall be one who has at
                    least 10% of the market for products within scope of the
                    Licensed Patents.

               G.   Under this Article XIV Yale shall have ninety (90) days
                    within which to initiate any action contemplated by
                    subsection F(i) and Enzo shall not be permitted to bring any
                    suit against an infringer while an action by Yale with
                    respect to the same patent is pending against that or
                    another infringer."

          8. Article XV, Section C of the License Agreement shall be and hereby
is amended to read as follows:

                    "Ownership and legal title to all inventions, patent
               applications and prospective patents which may issue and which
               are sponsored or are made jointly by Enzo and Yale or their
               employees and which are related to the field of art covered by
               the LICENSED PATENTS and made pursuant to Yale's and Enzo's
               further research efforts, under a written agreement stipulating
               such sponsorship by Enzo or joint effort by Enzo and Yale and
               referring to this Section of this Agreement, shall remain with
               Yale. Enzo shall have, and hereby is granted, a limited EXCLUSIVE
               LICENSE for a term defined in such agreement and a residual
               NONEXCLUSIVE LICENSE for the life of the patent as described in
               Article IIC to make, use and sell embodiments of said inventions.
               The filing and prosecution of patent applications with respect to
               such inventions shall be carried out in accordance with the
               provisions of Article IV of this


                                        5

  

               Agreement, Enzo shall use its best efforts to provide copies of
               all documents pertaining to the filing and prosecution of such
               patent applications to Yale for comment in advance of filing. Any
               written agreement referred to in this Article XVC shall be
               binding upon on Yale only if signed by a representative duly
               authorized by vote of the Yale Corporation to execute funding
               agreements on behalf of Yale."

          9. Enzo hereby releases Yale and its Officers, fellows, employees
(including without limitation Dr. David Ward) and agents from and against any
and all claims, demands, causes of action and liability arising out of any and
all acts or omissions heretofore by Yale or its employees or agents within the
scope of his or their employment or agency and relating to the subject matter of
the invention described in U.S. Patent Application Serial No. 503,298 (and
corresponding foreign applications, any divisional, continuation or substitute
patent applications, and any patents issued therefrom) or of the License
Agreement as related thereto.


          IN WITNESS WHEREOF, the parties have hereby executed this Agreement as
of the day above written by their duly authorized representatives.

                               YALE UNIVERSITY


                               By:
                                  ------------------------------------------
                                        Its VICE PRESIDENT FOR FINANCE


                               ENZO BIOCHEM, INC.


                               By:
                                  ------------------------------------------
                                        Its E.V.P.




                                        6

  

YALE UNIVERSITY

July 18, 1996

Dr. Elazer Rabbani
Enzo Biochem, Inc.
575 Fifth Avenue
New York, NY  10017

Dear Dr. Rabbani:

          Yale University has now concluded its investigation of Enzo's
compliance with the material terms and conditions of the Yale-Enzo Agreement.

          Based upon the information made available to us, and Enzo's
representations as to the accuracy and completeness of such information, the
University has concluded that Enzo was in compliance with its obligations to
Yale as of January 1, 1996. Accordingly, Enzo is entitled to exercise the option
provided by Paragraph 4 of the 1986 Amendment to the 1981 Yale-Enzo Agreement to
extend the term of its Exclusive License.

          In light of Mr. Fedus' letter of October 31, 1995, which we have
interpreted as indicating Enzo's desire to exercise the extension option, it is
the position of the University that Enzo's option has now been exercised, and
that the term of Enzo's Exclusive License has, since January 1, 1996, been
extended, subject to the terms of the existing Yale-Enzo Agreement of 1981, as
amended, "until the expiration of the life of the first U.S. Patent to issue
under U.S. Patent Application Serial No. 255,223 or if no such patent shall
issue, April 17, 2003."

          As you may know, I only recently became Director of the Office of
Cooperative Research. I look forward to meeting with you upon your return from
Europe. I hope this letter which disposes the issues of compliance and the
exercise of the January 1, 1996 option will allow the two of us to initiate
discussions on how to conduct this relationship in a way that benefits both Enzo
and Yale.

Sincerely yours,

Gregory E. Gardiner
- ----------------------------
Gregory E. Gardiner, Ph.D.
Director

cc:   J. L. Auerbach
      R. J. Bickerton
      W. D. Stempel