EXHIBIT 5
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                                                                28 February 1994

HAND DELIVERED
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Martin Marietta Corporation
6801 Rockledge Drive
Bethesda, Maryland  20817

                Re:  Martin Marietta Corporation Performance
                     Sharing Plan for Puerto Rico Employees

Ladies and Gentleman:

         I submit this opinion letter to you in connection with the 
registration statement on Form S-8 (the "Registration Statement") being filed
with the Securities and Exchange Commission on the date hereof. The
Registration Statement registers shares of common stock of the Martin Marietta
Corporation ("Corporation") for use in connection with the Martin Marietta
Corporation Performance Sharing Plan for Puerto Rico Employees ("Plan"). The
Plan contemplates that such common stock may be treasury or authorized but
unissued common stock or may be acquired in the open market. As Assistant
General Counsel of the Corporation, I have examined such corporate records,
certificates and other documents and have reviewed such questions of law as I
deemed necessary or appropriate for the purposes of this opinion.

         Based upon that examination and review, I advise you that in my 
opinion:

     (1)  the Corporation has been duly incorporated and is a validly existing
corporation under the laws of the State of Maryland, and

     (2)  to the extent that the operation of the Plan results in the issuance
of common stock, such shares of common stock have been duly and validly 
authorized and, when issued in accordance with the terms set forth in the 
Registration Statement, will be legally issued, fully paid and nonassessable.

         I hereby consent to the filing of this opinion as an exhibit to the 
Registration Statement and to the reference to my opinion in the Registration 
Statement.

                                                 Very truly yours,

                                                 Stephen M. Piper