EXHIBIT 5.1
                                                       
                                 May 26, 1998

TRIMBLE NAVIGATION LIMITED
645 North Mary Avenue
Sunnyvale, California 94088

         RE:      REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

         We have examined the Registration  Statement on Form S-8 to be filed by
you with the Securities and Exchange  Commission on or about May 26, 1998 (the
"Registration  Statement"),  in  connection  with  the  registration  under  the
Securities  Act of 1933,  as amended,  of 650,000  shares of your  Common  Stock
reserved for issuance under the 1988 Employee Stock Purchase Plan and of 600,000
shares of your Common Stock  reserved  for issuance  under the 1993 Stock Option
Plan (the  "Plans").  As your legal  counsel,  we have examined the  proceedings
taken and  proposed  to be taken in  connection  with the  issuance,  sale,  and
payment of consideration for the shares to be issued under the Plans.

         It is our opinion that,  when issued and sold in the manner referred to
in the Plans and  pursuant to the  agreements  which  accompany  the Plans,  the
shares will be legally and validly issued, fully paid, and non-assessable.

         We consent to the use of this opinion as an exhibit to the Registration
Statement and further  consent to the use of our name wherever  appearing in the
Registration Statement and any amendments thereto.


                                           Very truly yours,

                                           WILSON, SONSINI, GOODRICH & ROSATI
                                           Professional Corporation

                                           By:  /s/John B. Goodrich
                                                   John B. Goodrich


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