Exhibit 32.1

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In  connection  with the  Quarterly  Report  of  First  Financial  Bancorp  (the
"Company") on Form 10-Q for the period  ending  September 30, 2003 as filed with
the Securities  and Exchange  Commission on the date hereof (the  "Report"),  I,
Leon S. Zimmerman,  Chief Executive Officer of the Company, certify, pursuant to
18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley
Act of 2002, that:

         (1)      The Report fully  complies  with the  requirements  of Section
                  13(a) or 15(d) of the Securities Exchange Act of 1934; and

         (2)      The information  contained in the Report fairly  presents,  in
                  all material respects,  the financial condition and results of
                  operations of the Company.

November 12, 2003                                    /s/Leon S. Zimmerman
                                                     ---------------------------
                                                     Chief Executive Officer

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