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                                   EXHIBIT 5
                                                               September 7, 1999

First Financial Bancorp.
300 High Street
Hamilton OH  45012-0476

         Re:      First Financial Bancorp. Form S-8 Registration Statement
                  First Financial Bancorp. 1999 Stock Incentive Plan for
                  Officers and Employees
                  First Financial Bancorp. 1999 Stock Option Plan for
                  Non-Employee Directors

Gentlemen:

         We are counsel for First Financial Bancorp., an Ohio corporation (the
"Company"), which is named as the registrant in the Registration Statement on
Form S-8 (the "Registration Statement") that is being filed on or about
September 7, 1999 with the Securities and Exchange Commission (the "Commission")
for the purpose of registering under the Securities Act of 1933, as amended (the
"Act"), 6,000,000 common shares, without par value (the "Common Shares"), of the
Company to be offered pursuant to the First Financial Bancorp. 1999 Stock
Incentive Plan for Officers and Employees (the "Incentive Plan") and 500,000
Common Shares of the Company to be offered pursuant to the First Financial
Bancorp. 1999 Stock Option Plan for Non-Employee Directors (the "Option Plan")
(collectively the "Plans").

         As counsel for the Company, we have participated in the preparation of
the Registration Statement. In addition, we are generally familiar with the
records and proceedings of the Company. Furthermore, we have examined and relied
on the originals or copies, certified or otherwise identified to our
satisfaction, of corporate records or documents of the Company and such
representations of officers of the Company as we have deemed appropriate.

         With respect to the Common Shares offered pursuant to the Plans and
registered pursuant to the Registration Statement as filed and as it may be
amended, it is our opinion that the Common Shares, when distributed pursuant to
the terms of the Incentive Plan or when issued and paid for pursuant to the
terms of the Incentive Plan or the Option Plan, will be validly issued, fully
paid and non-assessable.

         We hereby consent to the filing of this opinion with the Commission.

                                           Very truly yours,

                                           Frost & Jacobs LLP