<DOCUMENT>
<TYPE>EX-5
<SEQUENCE>2
<FILENAME>d83242ex5.txt
<DESCRIPTION>PROPOSED OPINION OF BRUNINI GRANTHAM GROVER HEWES
<TEXT>

<PAGE>   1
                                                                       EXHIBIT 5

              [BRUNINI, GRANTHAM, GROWER & HEWES, PLLC LETTERHEAD]

                              ______________, 2001

Board of Directors and Shareholders Barret Bancorp, Inc.

        We have acted as counsel to Trustmark Corporation, a Mississippi
corporation ("Trustmark") and Trustmark National Bank, a national banking
association ("Trustmark Bank") in connection with a Merger Agreement dated as of
December 12, 2000 (the "Merger Agreement") by and among Trustmark, Trustmark
Bank, Barret Bancorp, Inc., a Tennessee corporation ("Barret"), Peoples Bank, a
Tennessee banking corporation ("Peoples") and Somerville Bank & Trust Company, a
Tennessee banking corporation ("Somerville"). In connection with this
representation, we have examined the charter and bylaws of Trustmark Bank, the
articles of incorporation and bylaws of Trustmark, the corporate proceedings of
Trustmark and Trustmark Bank in connection with the transactions contemplated by
the Merger Agreement and such other documents and instruments as we deemed
necessary to render the following opinions.

        Based upon the foregoing, we are of the opinion that:

        1. Trustmark Bank is duly organized, validly existing and in good
        standing as a national banking association.

        2. Trustmark is duly organized, validly existing and in good standing
        as a business corporation under the laws of the State of Mississippi.

        3. The outstanding shares of Trustmark are validly issued, fully paid
        and nonassemble. The shares of Trustmark common stock to be issued as a
        result of the Merger shall be, upon execution and delivery, duly
        authorized, validly issued, fully paid and nonassessable shares of the
        common stock of Trustmark and are registered on Form S-4 pursuant to the
        Securities Act of 1933.

        4. The Merger Agreement is valid, binding and enforceable against
        Trustmark and Trustmark Bank in accordance with its terms, subject to
        applicable bankruptcy, insolvency, moratorium, reorganization and other
        laws of general application relating to or affecting the enforcement of
        creditors' rights generally.

        5. The Merger has been duly authorized by all requisite corporate and
        shareholder action of Trustmark and Trustmark Bank.

        6. To the best of our knowledge, following diligent inquiry, but without
        independent verification of facts certified by appropriate officials of
        Trustmark and Trustmark Bank and relied upon by us, neither of Trustmark
        or Trustmark Bank has made any material misrepresentation, materially
        breached any warranty or materially breached any covenant or condition
        in the Merger Agreement or in any document, statement, list or schedule
        referred to therein.

Very truly yours,

BRUNINI, GRANTHAM, GROWER & HEWES, PLLC



Robert D. Drinkwater

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