EXHIBIT 31 (a)

                                 CERTIFICATIONS

In connection with the Quarterly Report on Form 10-Q of Enzo Biochem, Inc. ("the
Company") for the fiscal  quarter  October 31, 2005 as filed with the Securities
and Exchange  Commission on the date hereof,  I, Elazar  Rabbani,  Ph.D.,  Chief
Executive  Officer of the Company,  certify,  pursuant to 18 U.S.C. ss. 1350, as
adopted pursuant to ss. 302 of the Sarbanes-Oxley Act of 2002, that:

1.   I have reviewed this Quarterly Report on Form 10-Q of Enzo Biochem, Inc.

2.   Based on my knowledge, this report does not contain any untrue statement of
     a material  fact or omit to state a  material  fact  necessary  to make the
     statements made, in light of the circumstances  under which such statements
     were made,  not  misleading  with  respect  to the  period  covered by this
     report;

3.   Based on my  knowledge,  the  financial  statements,  and  other  financial
     information  included  in  this  report,  fairly  present  in all  material
     respects the financial  condition,  results of operations and cash flows of
     the Company as of, and for, the periods presented in this report;

4.   The  Company's  other  certifying  officer(s)  and  I are  responsible  for
     establishing and maintaining disclosure controls and procedures (as defined
     in  Exchange  Act Rules 13a - 15(e) and 15d - 15(e)) and  internal  control
     over  financial  reporting (as defined in Exchange Act Rules  13a-15(f) and
     15d-15(f)) for the Company and have:

     (a)  Designed  such  disclosure  controls  and  procedures,  or caused such
          disclosure   controls  and   procedures  to  be  designed   under  our
          supervision,  to ensure  that  material  information  relating  to the
          Company, including its consolidated subsidiaries,  is made known to us
          by others  within those  entities,  particularly  during the period in
          which this report is being prepared;

     (b)  Designed such internal  control over  financial  reporting,  or caused
          such internal  control over  financial  reporting to be designed under
          our  supervision,   to  provide  reasonable  assurance  regarding  the
          reliability  of financial  reporting and the  preparation of financial
          statements for external purposes in accordance with generally accepted
          accounting principals;

     (c)  Evaluated the effectiveness of the Company's  disclosure  controls and
          procedures  and  presented  in this report our  conclusions  about the
          effectiveness of the disclosure controls and procedures, as of the end
          of the period covered by this report based on such evaluation; and

     (d)  Disclosed in this report any change in the Company's  internal control
          over  financial  reporting  that occurred  during the  Company's  most
          recent fiscal quarter that has materially  affected,  or is reasonably
          likely to  materially  affect,  the  Company's  internal  control over
          financial reporting; and

5.   The Company's other  certifying  officer(s) and I have disclosed,  based on
     our most recent evaluation of internal control over financial reporting, to
     the Company's  auditors and the audit  committee of the Company's  board of
     directors (or persons performing the equivalent functions):

     (a)  All significant  deficiencies and material weaknesses in the design or
          operation  of internal  control  over  financial  reporting  which are
          reasonably likely to adversely affect the Company's ability to record,
          process, summarize and report financial information; and

     (b)  Any fraud, whether or not material,  that involves management or other
          employees  who  have a  significant  role  in the  Company's  internal
          control over financial reporting.

Date: December 12, 2005
                                                   By: /s/ Elazar Rabbani, Ph.D.
                                                       -------------------------
                                                   Elazar Rabbani, Ph.D.
                                                   Chief Executive Officer