Exhibit 99.1

                          SECTION 906 CEO CERTIFICATION

I, Joel F. Gemunder, President and Chief Executive Officer of Omnicare, Inc.
(the "Company"), do hereby certify in accordance with 18 U.S.C. 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that:

1.   The Quarterly Report on Form 10-Q of the Company for the period ended March
     31, 2003 (the "Periodic Report") fully complies with the requirements of
     section 13(a) or 15(d) of the Securities Exchange Act of 1934 (15 U.S.C.
     78m or 78o(d)) and

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

Dated: May 15, 2003


                                           /s/ Joel F. Gemunder
                                           -------------------------------------
                                           Joel F. Gemunder
                                           President and Chief Executive Officer