EXHIBIT 5.1


February 14, 2003



3M Company
3M Center
St. Paul, MN 55144

         Re:  3M Company Liquid Yield Option(TM) Notes due 2032 and common stock
              issuable upon conversion

Ladies and Gentlemen:

         I am Assistant General Counsel of 3M Company, a Delaware corporation
(the "Company"), and as such I have acted as counsel in connection with the
registration of $639,000,000 aggregate principal amount of the Company's Liquid
Yield Option(TM) Notes due 2032 (the "LYONs") and the shares of common stock
issuable upon conversion of the LYONs (the "Common Stock" and, together with the
LYONs, the "Securities") by the Company under the Securities Act of 1933, as
amended (the "Act"), on Form S-3 to be filed with the Securities and Exchange
Commission on the date hereof (the "Registration Statement"). Capitalized terms
used herein but not otherwise defined shall have the meaning assigned to them in
the Registration Statement.

         In connection with the foregoing, I have examined, or am familiar with,
originals, or copies, certified or otherwise, identified to my satisfaction, of
such documents, corporate records and other instruments as I have deemed
necessary for the purpose of this opinion. Based up such review of law and facts
as I have deemed appropriate under the circumstances, I am of the opinion that:

                  (i) The LYONs have been duly authorized by all necessary
         corporate action of the Company and constitute legal, valid and binding
         obligations of the Company, enforceable against the Company in
         accordance with their terms and the terms of the Indenture, except as
         the enforcement thereof may be limited by (i) bankruptcy, insolvency
         (including, without limitation, all laws relating to fraudulent
         transfers), reorganization, moratorium or other similar laws relating
         to or affecting enforcement of creditors' rights generally, or (ii) by
         general principles of equity (regardless of whether enforcement is
         considered in a proceeding in equity or at law).

                  (ii) The shares of Common Stock issuable upon conversion of
         the LYONs have been duly authorized and reserved for issuance upon such
         conversion by all necessary corporate action and such shares, when
         issued upon such conversion in accordance with the terms of the
         Indenture, will be legally issued and will be fully paid and
         non-assessable.



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         In rendering such opinions, I may rely as to matters of fact, to the
extent I deem proper, on certificates of responsible officers of the Company and
certificates or other written statements of officials of jurisdictions having
custody of documents respecting the corporate existence or good standing of the
Company. This opinion is limited to the Federal laws of the United States and
the laws of the State of New York and the General Corporate Laws of the State of
Delaware (including the statutory provisions and all applicable provisions of
the Delaware Constitution and reported judicial decisions interpreting the
General Corporate Laws of the State of Delaware).

         I consent to the filing of this opinion by the Company as an exhibit to
the Registration Statement and to the use of my name under the heading "Legal
Matters" in the Registration Statement. In giving the foregoing consent,
however, I do not admit that I come within the category of person whose consent
is required under Section 7 of the Act or the rules and regulations of the
Commission promulgated thereunder.


                                       Sincerely yours,

                                       /s/ Gregg M. Larson
                                       -----------------------
                                       Gregg M. Larson



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