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                                                                    EXHIBIT 5.1

                                   Law Offices
                      ELIAS, MATZ, TIERNAN & HERRICK L.L.P.
                                   12th Floor
                              734 15th Street, N.W.
                             Washington, D.C. 20005
                            Telephone (202) 347-0300

                                  April 4, 1997


Board of Directors
Peoples Heritage Financial Group, Inc.
One Portland Square
P.O. Box 9540
Portland, Maine  04112-9540

Ladies and Gentlemen:

      In connection with the registration under the Securities Act of 1933, as
amended (the "Act"), of $100,000,000 aggregate principal amount of Junior
Subordinated Deferrable Interest Debentures (the "Debt Securities") of Peoples
Heritage Financial Group, Inc., a Maine corporation (the "Corporation"),
$100,000,000 aggregate liquidation amount of Capital Securities (the "Capital
Securities") of Peoples Heritage Capital Trust I, a business trust created under
the laws of the State of Delaware (the "Issuer"), and the Guarantee with respect
to the Capital Securities (the "Guarantee") to be executed and delivered by the
Corporation for the benefit of the holders from time to time of the Capital
Securities, we, as your counsel, have examined such corporate records,
certificates and other documents, and such questions of law, as we have
considered necessary or appropriate for the purposes of this opinion.

      Upon the basis of such examination, we advise you that, when:

            (i) the Registration Statement relating to the Debt Securities, the
      Capital Securities and the Guarantee has become effective under the Act;

            (ii) the Guarantee Agreement relating to the Guarantee with respect
      to the Capital Securities of the Issuer has been duly executed and
      delivered;

            (iii) the Debt Securities have been duly executed and authenticated
      in accordance with the Indenture and issued and delivered as contemplated
      in the Registration Statement; and
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Board of Directors
April 4, 1997
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           (iv) the Capital Securities have been duly executed in accordance
      with the Amended and Restated Declaration of Trust of the Issuer and
      issued and delivered as contemplated in the Registration Statement,

the Debt Securities and the Guarantee relating to the Capital Securities of the
Issuer will constitute valid and legally binding obligations of the Corporation,
subject to bankruptcy, insolvency, fraudulent transfer, reorganization,
moratorium and similar laws of general applicability relating to or affecting
creditors' rights and to general equity principles.

      The foregoing opinion is limited to the Federal laws of the United States,
the laws of the State of New York and the laws of the State of Maine, and we are
expressing no opinion as to the effect of the laws of any other jurisdiction.

      We understand that you have received an opinion regarding the Capital
Securities from Richards, Layton & Finger, LLP, special Delaware counsel for the
Corporation and the Issuer. We are expressing no opinion with respect to the
matters contained in such opinion.

      Also, we have relied as to certain matters on information obtained from
public officials, officers of the Corporation and other sources believed by us
to be responsible.

      We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the references to us under the heading "Validity
of New Securities" in the Prospectus. 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 Act.

                                    Very truly yours,

                                    ELIAS, MATZ, TIERNAN & HERRICK L.L.P



                                    By: /s/Gerard L. Hawkins
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                                        Gerard L. Hawkins, a Partner