SECURITIES AND EXCHANGE COMMISSION

                             WASHINGTON, D.C. 20549


                                    FORM 8-A


                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                    PURSUANT TO SECTION 12(B) OR 12(G) OF THE
                         SECURITIES EXCHANGE ACT OF 1934


                          Financial Institutions, Inc.
- --------------------------------------------------------------------------------
             (Exact Name of Registrant as Specified in Its Charter)


         New York                                                16-0816610
- --------------------------------------------------------------------------------
(State of Incorporation                                       (I.R.S. Employer
        or Organization)                                     Identification No.)


         220 Liberty Street, Warsaw, New York                    14569
- --------------------------------------------------------------------------------
         (Address of principal executive offices)                (Zip Code)

- --------------------------------------------------------------------------------
If this form relates to the registration of a class of debt securities and is
effective upon filing pursuant to General Instruction A.(c)(1), please check the
following box. |_|

If this form relates to the registration of a class of debt securities and is to
become effective simultaneously with the effectiveness of a concurrent
registration statement under the Securities Act of 1933 pursuant to General
Instruction A.(c)(2), please check the following box. |_|

If this form relates to the registration of a class of securities pursuant to
Section 12(b) of the Exchange Act and is effective pursuant to General
Instruction A.(c), check the following box. |_|

If this form relates to the registration of a class of securities pursuant to
Section 12(g) of the Exchange Act and is effective pursuant to General
Instruction A.(d), check the following box. |X|

Securities Act registration statement file number to which this form relates:
                                                                       333-76865
                                                                 (if applicable)

Securities to be registered pursuant to Section 12(b) of the Act:

Title of each class                               Name of each exchange on which
to be so Registered                               each class is to be registered
- -------------------                               ------------------------------

- --------------------------------            ------------------------------------

Securities to be registered pursuant to Section 12(g) of the Act:

                     Common Stock, par value $.01 per share
                     --------------------------------------
                                (Title of Class)






                                      - 2 -


ITEM 1.      DESCRIPTION OF REGISTRANT'S SECURITIES TO BE REGISTERED.

         The Registrant incorporates by reference herein the information set
forth under the caption "Description of Securities of the Company" set forth in
its preliminary prospectus dated June 23, 1999 included in Amendment No. 2 to
its Registration Statement on Form S-1 (Registration No. 333-76865), filed with
the Securities and Exchange Commission (the "Commission") on June 23, 1999, as
such information may be amended in the final prospectus included or deemed to be
included in such Registration Statement, as hereafter amended, in the form
declared effective by the Commission (the "Registration Statement"). This Form
8-A is filed to register the Registrant's class of Common Stock pursuant to
Section 12(g) of the Securities Exchange Act of 1934, as amended ("Exchange
Act"), concurrently with the registration of shares of Common Stock under the
Securities Act of 1933, as amended ("Securities Act"), and in accordance with
Rule 12d1-2 promulgated under the Exchange Act, will become effective
concurrently with the effectiveness of the Registration Statement under the
Securities Act.

ITEM 2.      EXHIBITS

         The following exhibits are incorporated herein by reference to previous
filings made by the Registrant with the Securities and Exchange Commission:

  Exhibit
  Number                         Exhibit Name
  ------                         ------------

  3.1        Amended and Restated Certificate of Incorporation of the Registrant
             is incorporated by reference to Exhibit 3.1 to the Registrant's
             Registration Statement on Form S-1 filed with the Securities and
             Exchange Commission, File No. 33-76865 (the "S-1")

  3.2        By-laws of Registrant are incorporated by reference to Exhibit 3.2
             to the S-1

  4.1        Form of Certificate of Registrant's Common Stock is incorporated by
             reference to Exhibit 4.1 to the S-1





                                      -3-

                                    SIGNATURE

         Pursuant to the requirements of Section 12 of the Securities Exchange
Act of 1934, the registrant has duly caused this registration statement to be
signed on its behalf by the undersigned, thereunto duly authorized.


Dated:     June 22, 1999                          FINANCIAL INSTITUTIONS, INC.


                                                  By:  /s/ Ronald A. Miller
                                                           Ronald A. Miller
                                                           Senior Vice President