Exhibit 5
                                                                       ---------

                          NUTTER, McCLENNEN & FISH, LLP

                                ATTORNEYS AT LAW

                             ONE INTERNATIONAL PLACE
                        BOSTON, MASSACHUSETTS 02110-2699

            TELEPHONE: 617-439-2000           FACSIMILE: 617-973-9748

CAPE COD OFFICE                                               DIRECT DIAL NUMBER
HYANNIS, MASSACHUSETTS


                               September 25, 1998


GenRad, Inc.
7 Technology Park Drive
Westford, MA  01886

Gentlemen/Ladies:

         Reference is made to the registration statement on Form S-8 (the
"Registration Statement") which GenRad, Inc. (the "Company") is filing
concurrently herewith with the Securities and Exchange Commission under the
Securities Act of 1933, as amended, (the "Securities Act"), with respect to (i)
2,500,000 shares of the Company's common stock, $1.00 par value per share (the
"Common Stock"), issuable pursuant to the Company's 1991 Equity Incentive Plan,
as amended to date (the "Incentive Plan"), (ii) 50,000 shares of Common Stock
issuable pursuant to the Company's 1991 Directors' Stock Option Plan, as amended
to date, (the "1991 Director Plan"), and (iii) 50,000 shares of Common Stock
issuable pursuant to the Company's 1994 Director Restricted Stock Plan, as
amended to date (together with the Incentive Plan and the 1991 Director Plan,
the "Plans"), and an indeterminate number of shares of such Common Stock which
may be issued or become issuable under the Plans by reason of stock dividends,
stock splits or other recapitalizations executed hereafter.

         We have acted as legal counsel for the Company in connection with the
adoption of and amendments to the Plans, are familiar with the Company's
Articles of Organization and By-laws, both as amended to date (collectively, the
"Organizational Documents"), and have examined such other documents as we have
deemed necessary for this opinion. Based upon the foregoing, we are of the
opinion that:

         1. When issued and paid for in compliance with the terms of the
respective Plan, the Organizational Documents and the Massachusetts Business
Corporation Law, the 2,600,000 shares of Common Stock referred to above will be
duly and validly issued, fully paid and non-assessable; and

         2. The additional shares of Common Stock which may become issuable
under the Plans by reason of stock dividends, stock splits or other
recapitalizations hereafter executed, if and when issued in accordance with the
terms of the respective Plan and upon compliance with the applicable provisions
of law and of the Company's Organizational Documents, will be duly and validly
issued, fully paid and non-assessable.

        We understand that this opinion letter is to be used in connection with
the Registration Statement and hereby consent to the filing of this opinion
letter with and as a part of the Registration Statement and of any amendments
thereto. It is understood that this opinion letter is to be used in connection
with the offer and sale of the aforesaid shares only while the Registration
Statement, as it may be amended from time to time as contemplated by Section
10(a)(3) of the Securities Act, is effective under the Securities Act.

                                             Very truly yours,
                                           
                                             /s/ Nutter, McClennen & Fish, LLP
                                                 -------------------------------
                                             Nutter, McClennen & Fish, LLP