1


                                                                     Exhibit 8.1








Writer's Direct Dial:  (212) 225-2540
E-Mail:  yreich@cgsh.com



                                January 16, 2001




Fifth Third Bancorp
38 Fountain Square Plaza
Cincinnati, Ohio 45263




Ladies and Gentlemen:

                  Reference is made to the Registration Statement on Form S-4
(as amended, the "Registration Statement") of Fifth Third Bancorp, an Ohio
corporation ("Fifth Third"), relating to the merger (the "Merger") of Old Kent
Financial Corporation, a Michigan corporation ("Old Kent"), with and into Fifth
Third Financial Corporation, an Ohio corporation and a wholly-owned subsidiary
of Fifth Third.

                  We have reviewed the discussion set forth in the section
entitled "The Merger - Material Federal Income Tax Consequences" in the
Registration Statement. In our opinion, such discussion, insofar as it relates
to matters of United States federal income tax law, is accurate in all material
respects.


                  We hereby consent to the filing of this opinion with the
Securities and Exchange Commission as an exhibit to the Registration Statement,
and to the references therein to us. In giving such consent, we do not thereby
admit that we are in the category of persons whose consent is required under
Section 7 of the Securities Act of 1933, as amended.

                                            Very truly yours,


                                            CLEARY, GOTTLIEB, STEEN & HAMILTON

                                            By: /S/ YARON Z. REICH
                                                ------------------
                                                Yaron Z. Reich, a Partner