1

                                   EXHIBIT 5.1

                           GOODWIN, PROCTER & HOAR LLP
                               COUNSELLORS AT LAW
                                 EXCHANGE PLACE
                        BOSTON, MASSACHUSETTS 02109-2881

                                  June 30, 2000

Brooktrout, Inc.
250 First Avenue, Suite 300
Needham, Massachusetts 02494
Attn: Eric R. Giler

Re:      Brooktrout, Inc. 1999 Stock Incentive Plan, as amended
         ------------------------------------------------------

Ladies and Gentlemen:

         This opinion is delivered in our capacity as counsel to Brooktrout,
Inc. (the "Company") in connection with the preparation and filing with the
Securities and Exchange Commission under the Securities Act of 1933, as amended
(the "Securities Act"), of a Registration Statement on Form S-8 (the
"Registration Statement") relating to 900,000 shares of the Company's common
stock, par value $.01 per share (the "Registered Shares"), which may be issued
pursuant to the Brooktrout, Inc. 1999 Stock Incentive Plan, as amended (the
"Plan").

         As counsel for the Company, we have examined copies of the Plan, the
Registration Statement, and the Company's Restated Articles of Organization, as
amended, and Amended and Restated By-laws, each as presently in effect, such
records of the corporate proceedings of the Company as deemed to be material and
such other certificates, receipts, records, and other documents as we have
deemed necessary or appropriate for the purposes of this opinion.

         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 Commonwealth of
Massachusetts, and also express no opinion with respect to the blue sky or
securities laws of any state, including Massachusetts.

         Based on the foregoing, we are of the opinion that, when the Registered
Shares are sold and paid for pursuant to the terms of the Plan, the Registered
Shares will be duly authorized, validly issued, fully paid and non-assessable by
the Company under the Business Corporation Law of The Commonwealth of
Massachusetts.

         The foregoing assumes that all requisite steps will be taken to comply
with the requirements of the Securities Act and applicable requirements of state
laws regulating the offer and sale of securities.

         We hereby consent to being named as counsel to the Company in the
Registration Statement and to the inclusion of this opinion as an exhibit to the
Registration Statement.

                                           Very truly yours,

                                           /s/ Goodwin, Procter & Hoar LLP
                                           GOODWIN, PROCTER & HOAR  LLP