Exhibit 31.1
                                CERTIFICATION OF
                             CHIEF EXECUTIVE OFFICER

I, Leon Zimmerman, certify that:

1.   I have  reviewed  this  quarterly  report on Form  10-Q of First  Financial
Bancorp for the quarter ended March 31, 2004;

2.   Based on my knowledge,  this  quarterly  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 quarterly
report;

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

4.   The  registrant's  other  certifying  officer  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)) for the registrant and we 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  registrant,  including  its
consolidated subsidiaries,  is made known to us by others within those entities,
particularly during the period in which this quarterly report is being prepared;

     (b) evaluated the effectiveness of the registrant'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

     (c)  disclosed  in this  quarterly  report any  change in the  registrant's
internal control over financial  reporting that occurred during the registrant's
most recent fiscal quarter (the  registrant's  fourth fiscal quarter in the case
of an annual report) that has materially  affected,  or is reasonably  likely to
materially  affect the registrant's  internal control over financial  reporting;
and

5.   The registrant's  other certifying  officer and I have disclosed,  based on
our most recent evaluation of internal control over financial reporting,  to the
registrant's  auditors  and the audit  committee  of the  registrant'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  registrant'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 registrant's  internal control over
financial reporting.

                                       /s/  Leon Zimmerman
                                       -----------------------------------------
                                       Leon Zimmerman
                                       President and Chief Executive Officer
                                       (Principal Executive Officer)

Dated:  May 12, 2004