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                                                                   EXHIBIT 8.1


                                December 12, 2000



M&T Bank Corporation
One M&T Plaza
Buffalo, NY   14203

Ladies and Gentlemen:

      You have requested our opinion as to certain federal income tax
consequences of the proposed merger (the "Merger") of Premier National Bancorp
Inc. ("Premier") with and into Olympia Financial Corp. ("Olympia"), a wholly
owned subsidiary of M&T Bank Corporation ("M&T").


      In preparing our opinion, and with your permission, we have assumed that
(1) the Merger will be consummated in accordance with the terms, conditions
and other provisions of the Agreement and Plan of Reorganization by and among
Premier, M&T and Olympia, dated as of July 9, 2000 (the "Reorganization
Agreement"), the Agreement and Plan of Merger by and between Premier and
Olympia and joined in by M&T, dated as of July 9, 2000, as amended on October
26, 2000 (as amended, the "Plan of Merger"), and the Option Agreement, (1) and
(2) all of the factual information, descriptions, representations and
assumptions set forth or referred to (a) in this letter (an advance copy of
which has been provided to you), (b) in the Reorganization Agreement, the Plan
of Merger and the Option Agreement (the "Agreements"), (c) in letters to us
from M&T and Olympia dated December 12, 2000, and from Premier dated December
12, 2000 (the "Letters"), and (d) in the Proxy Statement-Prospectus prepared in
connection with the Merger, are accurate and complete and will be accurate and
complete as of the effective time of the Merger (the "Effective Time").


      In our examination of such materials, we have assumed the genuineness of
all signatures, the legal capacity of all natural persons, the authenticity of
all documents submitted to us as originals, the conformity to original
documents of all documents submitted to us as copies, and the authenticity of
the originals of such documents. We have not independently verified any
factual matters relating to the Merger in connection with or apart from our
preparation of this opinion. Accordingly, our opinion does not


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(1) Terms not otherwise defined in this letter shall have the meanings
assigned to them in the Reorganization Agreement.





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December 12, 2000
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take into account any matters not set forth herein which might have been
disclosed by independent verification.





                                   OPINION

      Based on the foregoing, and subject to the qualifications and other
matters set forth herein, it is our opinion that for federal income tax
purposes:

      1.   The Merger will be treated as a reorganization within the meaning
           of Section 368(a) of the Internal Revenue Code of 1986, as amended
           (the "Code");

      2.   M&T, Premier and Olympia will each be a party to the reorganization
           within the meaning of Section 368(b) of the Code;

      3.   No gain or loss will be recognized by M&T, Olympia or Premier as a
           result of the Merger (except for amounts resulting from any
           required change in accounting methods or any income or deferred
           gain recognized under the relevant consolidated return
           regulations);

      4.   Premier shareholders who receive M&T common stock in exchange for
           all of their shares of Premier common stock will not recognize any
           gain or loss with respect to shares of M&T common stock received
           (except with respect to cash received instead of a fractional share
           interest in M&T common stock);

      5.   Each Premier shareholder who receives M&T common stock and cash
           (other than cash instead of a fractional share interest in M&T
           common stock) in exchange for the shareholder's shares of Premier
           common stock will recognize the gain, if any, realized by the
           shareholder, in an amount not in excess of the amount of cash
           received (other than cash received instead of a fractional share
           interest in M&T common stock), but will not recognize any loss on
           the exchange;

      6.   Each Premier shareholder's aggregate tax basis in any shares of M&T
           common stock received in the transaction (including fractional
           shares that are deemed to have been received and then redeemed)
           will be the same as the aggregate tax basis of the shares of
           Premier common stock surrendered by such shareholder for the M&T
           common stock, decreased by the amount of any cash received (other
           than cash received instead of a fractional share interest in M&T
           common stock) by the shareholder and increased by the amount of


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           income or gain recognized by the shareholder in the exchange (which
           does not include gain recognized in respect of fractional shares
           that are deemed to have been received and then redeemed); and

      7.   Each Premier shareholder's holding period in any shares of M&T
           common stock received in the transaction (including any fractional
           shares that are deemed to have been received and then redeemed)
           will, in each instance, include the period during which the shares
           of Premier common stock surrendered in exchange therefor were held,
           provided that such shares of Premier common stock were held as
           capital assets by the shareholder at the Effective Time.

      This opinion may not apply to a Premier shareholder that is subject to
special treatment under the Code, such as a shareholder that is a financial
institution, an insurance company, a dealer in securities or foreign
currencies, a trader in securities, a tax-exempt organization, a person who
holds shares of Premier common stock in an individual retirement account
(IRA), 401(k) plan or similar tax-favored account, a person who acquired
shares of Premier common stock pursuant to the exercise of an employee stock
option or otherwise as compensation or a person who holds shares of Premier
common stock as part of a hedge, straddle, conversion or constructive sale
transaction.

      Our opinion is limited to the foregoing federal income tax consequences
of the Merger, which are the only matters as to which you have requested our
opinion, and you must judge whether the matters addressed herein are
sufficient for your purposes. We do not address any other federal income tax
consequences of the Merger or other matters of federal law and have not
considered matters (including state or local tax consequences) arising under
the laws of any jurisdiction other than matters of federal law arising under
the laws of the United States.

      Our opinion is based on the understanding that the relevant facts are,
and will be, as of the Effective Time, as set forth or referred to in this
letter. If this understanding is incorrect or incomplete in any respect, our
opinion could be affected.

      Our opinion is also based on the Code, Treasury Regulations, case law,
and Internal Revenue Service rulings as they now exist. These authorities are
all subject to change and such change may be made with retroactive effect. We
can give no assurance that after any such change, our opinion would not be
different. Moreover, our opinion is not binding on the Internal Revenue
Service or the courts.



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      We undertake no responsibility to update or supplement this opinion.
This opinion letter is being rendered to M&T in connection with the Merger.
Only M&T may rely on this opinion letter, and only with respect to the Merger
described herein.

      We hereby consent to the filing with the Securities and Exchange
Commission of this opinion as an exhibit to the Registration Statement on Form
S-4 and to the reference to our firm under the heading "THE MERGER - Certain
Federal Income Tax Consequences" in the Proxy Statement-Prospectus contained
therein. 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.


                                Very truly yours,



                                 /s/ Arnold & Porter


                                 ARNOLD & PORTER