Document:

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                                                                  EXHIBIT 10.(w)

                                AMENDMENT NO. 1

                                       TO

                                   AGREEMENT

         AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT, dated as of July 13, 2000 and
effective retroactively as of May 5, 1999, by and among ENZO BIOCHEM, INC., a
New York corporation with offices at 60 Executive Blvd., Farmindgale, NY 11735
(the "Company") and Shahram Rabbani, an individual residing at 17 Catalina
Drive, Great Neck, NY 11021 (the "Executive").

                                    RECITALS
                                    --------

         Executive has been an executive of the Company since October 15, 1987
and possesses valuable experience, skills and know-how with respect to all
aspects of the Company's business. The parties hereto are party to an Agreement,
dated as of May 4, 1994 (the "Employment Agreement"), and desire to amend the
Employment Agreement as hereinafter set forth. The Company desires to continue
to employ Executive on the terms and conditions set forth in the Employment
Agreement, as amended hereby, and Executive is willing to continue such
employment on such terms and conditions.

         It is therefore hereby agreed by and between the parties as follows:

         1.       Amendments to Employment Agreement.

                  Section 1.2(a) is hereby amended in its entirety to read as
follows:

                  Except for earlier termination as provided in Section 4
hereof, the Executive's employment under this Agreement (the "Employment Term" )
shall be for an initial term (the "Initial Term") beginning on the date hereof
and ending on May 4, 2002. The Employment Term shall be automatically renewed
for an additional term (an "Additional Term") of two (2) years unless either
party hereto gives written notice to the other at least one hundred eighty (180)
days prior to the expiration of the Initial Term of such party's intention to
terminate the Executive's employment hereunder at the end of such Initial Term.
The Employment Term shall be automatically renewed for an indefinite number of
subsequent Additional Terms of two (2) years unless either party hereto gives
written notice to the other at least one hundred eighty (180) days prior to the
expiration of the Additional Term then in effect of such party's intention to
terminate the Executive's employment hereunder at the end of such Additional
Term.

                  Section 2.1 is hereby amended in its entirety to read as
follows:

                  Base Salary. As compensation for the Executive's employment
hereunder, the Executive shall be entitled to receive a base salary at a rate of
$250,000 per annum payable (and subject to withholding) in accordance with the
Company's normal payroll practices from time to time in effect, to be increased
to $280,000 per annum effective as of January 1, 2000. The base salary may be
increased, but not decreased, from time to time at the discretion of the Board.
(The base salary as increased from time to time being hereinafter referred to as
the "Base Salary.")

<PAGE>

         2.       Reaffirmation of Employment Agreement.
                  --------------------------------------

                  Except as provided herein, this Amendment No. 1 shall not
constitute a waiver or modification of any term, provision or condition of the
Employment Agreement; and all terms, conditions, agreements, provisions,
representations and warranties contained in the Employment Agreement shall
remain in full force and effect.

         3.       Governing Law.
                  --------------

                  This Amendment No. 1 shall be governed by, and construed and
enforced in accordance with, the laws of the State of New York, applicable to
agreements made and to be performed entirely in New York. In addition, each
party hereto irrevocably and unconditionally agrees that any suit, action or
other legal proceeding arising out of this Agreement may be brought only in the
State of New York.

         IN WITNESS WHEREOF, the parties have executed this Amendment No. 1 on
July 13, 2000.

                                        ENZO BIOCHEM, INC.

                                        /s/ Shahram Rabbani
                                        ----------------------------------------
                                        Name:  Shahram Rabbani
                                        Title: Chief Operating Officer

                                        EXECUTIVE:

                                        /s/ Elazar Rabbani
                                        ----------------------------------------
                                        Elazar Rabbani<PAGE>

                                                                  EXHIBIT 10.(x)

                                AMENDMENT NO. 1

                                       TO

                                   AGREEMENT

         AMENDMENT NO. 1 TO EMPLOYMENT AGREEMENT, dated as of July 13, 2000 and
effective retroactively as of May 5, 1999, by and among ENZO BIOCHEM, INC., a
New York corporation with offices at 60 Executive Blvd., Farmindgale, NY 11735
(the "Company") and Barry W. Weiner, an individual residing at 69 Fifth Avenue,
New York, NY 10003 (the "Executive").

                                    RECITALS
                                    --------

         Executive has been Executive Vice President of the Company since
October 15, 1987 and possesses valuable experience, skills and know-how with
respect to all aspects of the Company's business. The parties hereto are party
to an Agreement, dated as of May 4, 1994 (the "Employment Agreement"), and
desire to amend the Employment Agreement as hereinafter set forth. The Company
desires to continue to employ Executive on the terms and conditions set forth in
the Employment Agreement, as amended hereby, and Executive is willing to
continue such employment on such terms and conditions.

         It is therefore hereby agreed by and between the parties as follows:

         1.       Amendments to Employment Agreement.
                  -----------------------------------

                  Section 1.2(a) is hereby amended in its entirety to read as
follows:

                  Except for earlier termination as provided in Section 4
hereof, the Executive's employment under this Agreement (the "Employment Term" )
shall be for an initial term (the "Initial Term") beginning on the date hereof
and ending on May 4, 2002. The Employment Term shall be automatically renewed
for an additional term (an "Additional Term") of two (2) years unless either
party hereto gives written notice to the other at least one hundred eighty (180)
days prior to the expiration of the Initial Term of such party's intention to
terminate the Executive's employment hereunder at the end of such Initial Term.
The Employment Term shall be automatically renewed for an indefinite number of
subsequent Additional Terms of two (2) years unless either party hereto gives
written notice to the other at least one hundred eighty (180) days prior to the
expiration of the Additional Term then in effect of such party's intention to
terminate the Executive's employment hereunder at the end of such Additional
Term.

                  Section 2.1 is hereby amended in its entirety to read as
follows:

                  Base Salary. As compensation for the Executive's employment
hereunder, the Executive shall be entitled to receive a base salary at a rate of
$250,000 per annum payable (and subject to withholding) in accordance with the
Company's normal payroll practices from time to time in effect, to be increased
to $280,000 per annum effective as of January 1, 2000. The base salary may be
increased, but not decreased, from time to time at the discretion of the Board.
(The base salary as increased from time to time being hereinafter referred to as
the "Base Salary.")

<PAGE>

         2.       Reaffirmation of Employment Agreement.
                  --------------------------------------

                  Except as provided herein, this Amendment No. 1 shall not
constitute a waiver or modification of any term, provision or condition of the
Employment Agreement; and all terms, conditions, agreements, provisions,
representations and warranties contained in the Employment Agreement shall
remain in full force and effect.

         3.       Governing Law.
                  --------------

                  This Amendment No. 1 shall be governed by, and construed and
enforced in accordance with, the laws of the State of New York, applicable to
agreements made and to be performed entirely in New York. In addition, each
party hereto irrevocably and unconditionally agrees that any suit, action or
other legal proceeding arising out of this Agreement may be brought only in the
State of New York.

         IN WITNESS WHEREOF, the parties have executed this Amendment No. 1 on
July 13, 2000.

                                        ENZO BIOCHEM, INC.

                                        /s/ Shahram Rabbani
                                        ----------------------------------------
                                        Name:  Shahram Rabbani
                                        Title: Chief Operating Officer

                                        EXECUTIVE:

                                        /s/ Barry Weiner
                                        ----------------------------------------
                                        Barry W. Weiner<PAGE>

                                                                  EXHIBIT 10.(z)

                            THIRD AMENDMENT TO LEASE
                            ------------------------

         Agreement (this "Third Amendment") made as of the 1st day of January,
2000 by and between Pari Management Corporation, a New York corporation with an
address at 17 Catalina Drive, Kings Point, New York 11024 (hereinafter referred
to as "Landlord"), and Enzolabs, Inc., a New York corporation with an address at
60 Executive Boulevard, Farmingdale, New York 11735 (hereinafter referred to as
"Tenant").

         WHEREAS, Landlord and Tenant are parties to that certain lease between
them, dated December 20, 1989, as amended by that First Amendment to Lease dated
as of February __, 1991 and by that Second Amendment to Lease dated as of
January 1, 1993 (as amended, the "Lease"), for the premises known as 60
Executive Boulevard, Farmingdale, New York (the "Leased Premises");

         WHEREAS, Paragraph 34(a) of the Lease permits the construction of
additional Improvements upon the Land forming part of the Leased Premises and
Landlord to rent same to Tenant or other third parties;

         WHEREAS, construction of 3,000 rentable square feet of such additional
Improvements has been completed (the "Additional Space");

         WHEREAS, Paragraph 34(a) of the Lease provides Tenant with a Right of
First Refusal to lease the Additional Space; and

         WHEREAS, Tenant would like to lease the Additional Space from Landlord,
and Landlord would like to rent the Additional Space to Tenant.

         NOW THEREFORE, IT IS AGREED AS FOLLOWS:

         1.       Tenant has constructed and shall improve and complete the
Additional Space at its sole cost and expense in such a manner, design and
method as Landlord shall determine in its sole and absolute discretion, and
according to the further terms of the Lease.

         2.       Tenant shall lease the entire Additional Space from Landlord
as follows:

         a.       Upon the same terms and conditions as are contained in the
Lease;

         b.       For a term commencing on January 1, 2000 (the "Commencement
Date") and ending on the Lease Termination Date or the earlier date on which the
Lease expires;

         c.       At a rental equal to the rent per rentable square foot payable
by Tenant pursuant to the Lease (in addition to additional rent and
adjustments), multiplied by the number of rentable square feet in the Additional
Space (which the parties hereto confirm shall be 3,000);

<PAGE>

         d.       With additional rental and adjustments payable pursuant to the
terms of the Lease except that, notwithstanding anything to the contrary
contained in this Third Amendment or in the Lease, with respect to the
Additional Space only, for additional rent and adjustments provided for under
the Lease which are calculated utilizing a base year, the Base Year shall be
deemed to mean the full calendar year immediately prior to the calendar year in
which the Commencement Date occurs;

         e.       In its "as is" condition on the Commencement Date; and

         f.       Tenant shall, on the Commencement Date, deposit with Landlord
a sum equal to two (2) months rent for the Additional Space as an additional
Security Deposit to be held pursuant to Paragraph 33 of the Lease.

         3.       Except as modified by this Third Amendment, all of the other
terms and conditions contained in the Lease are hereby ratified and confirmed
and shall remain in full force and effect.

         4.       If the terms and provisions contained in this Third Amendment
conflict with the terms and provisions of the Lease, the terms and conditions of
this Third Amendment shall prevail. All of the capitalized terms contained but
not defined herein shall have the same meaning as specified in the Lease.

         5.       This Third Amendment cannot be changed or terminated orally
and cannot be orally waived. The parties represent to each other that they are
authorized to execute this Third Amendment and that all applicable corporate
approvals have been obtained.

                                        Pari Management Corporation,
                                        Landlord

                                        By: /s/ Shahram Rabbani
                                           -------------------------------------

                                        Enzolabs, Inc.,
                                        Tenant

                                        By: /s/ Herb Bass
                                           -------------------------------------

                                       2

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