EXHIBIT 32.1

                             FIRST FINANCIAL BANCORP
              CERTIFICATION OF CHIEF EXECUTIVE OFFICER 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 ended June 30,  2004,  as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Leon S.
Zimmerman,  Chief Executive Officer of the Company, hereby 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.




August 12, 2004                                    /S/LEON S. ZIMMERMAN
                                                   -----------------------
                                                   Chief Executive Officer


                                       23