Exhibit 5.1

                            Goodwin, Procter & Hoar
               A Partnership Including Professional Corporations
                               Counsellors at Law
                                 Exchange Place
                        Boston, Massachusetts 02109-2881


                               September 11, 1995



Dynatech Corporation
3 New England Executive Park
Burlington, MA 01803

         Re:  LEGALITY OF SECURITIES

Gentlemen:

         This  opinion is  delivered  in our  capacity  as  counsel to  Dynatech
Corporation  (the  "Company")  in  connection  with the  Company's  registration
statement on Form S-3 (the  "Registration  Statement") filed with the Securities
and Exchange  Commission under the Securities Act of 1933, as amended,  relating
to 688,096 shares of the Company's  common stock,  $.20 par value per share (the
"Shares").

         We have  examined  the  Articles of  Organization  of the  Company,  as
amended  to the date  hereof  and on file with the  Massachusetts  Secretary  of
State; the Bylaws of the Company;  such records of corporate  proceedings of the
Company  as  we  deem  appropriate  for  the  purposes  of  this  opinion;   the
Registration Statement and the exhibits thereto.

         We  are  attorneys   admitted  to  practice  in  The   Commonwealth  of
Massachusetts.  We express no opinion  concerning the laws of any  jurisdictions
other  than  the  laws of the  United  States  of  America  and the  laws of the
Commonwealth of Massachusetts.

         Based upon the  foregoing,  we are of the  opinion  that the Shares are
legally issued, fully paid and nonassessable.

         We hereby  consent  to being  named as  counsel  to the  Company in the
Registration  Statement, to the references therein to our firm under the caption
"Legal  Matters"  and to the  inclusion  of this  opinion  as an  exhibit to the
Registration Statement.

                               Very truly yours,




                              GOODWIN, PROCTER & HOAR