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 Financial Institutions, Inc. (the “Company”) on Form 10-Q for the period ending September 30, 2005 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, Peter G. Humphrey, Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. § 1350, as adopted pursuant to § 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 result of operations of the Company.

November 4, 2005

/s/ Peter G. Humphrey

Peter G. Humphrey
Chief Executive Officer

A signed original of this written statement required by Section 906 has been provided to Financial Institutions, Inc. and will be retained by Financial Institutions, Inc. and furnished to the Securities and Exchange Commission or its staff upon request.