EXHIBIT 5.1

                    [GOODWIN, PROCTER & HOAR LLP LETTERHEAD]


                                January 17, 2001

Harvard Bioscience, Inc.
84 October Hill Road
Holliston, Massachusetts 01746-1371

Ladies and Gentlemen:

         Re:      REGISTRATION STATEMENT ON FORM S-8

         This opinion is delivered in our capacity as counsel to Harvard
Bioscience, 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 "Act") of a Registration Statement on Form S-8 (the "Registration
Statement") relating to 4,849,096 shares of Common Stock, par value $.01 per
share (the "Registered Shares") which the Company may issue pursuant to the
Harvard Bioscience, Inc. 2000 Stock Option and Incentive Plan, the Harvard
Apparatus, Inc. 1996 Stock Option and Grant Plan and the Harvard Bioscience,
Inc. Employee Stock Purchase Plan (the "Plans").

         As counsel for the Company, we have examined copies of the Plans and
the Company's Second Amended and Restated Certificate of Incorporation and
Amended and Restated By-laws, each as presently in effect, and such records,
certificates and other documents of the Company 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 jurisdiction
other than the laws of the United States of America, The Commonwealth of
Massachusetts and the Delaware General Corporation Law.

         Based on the foregoing, we are of the opinion that upon the issuance
and delivery of the Registered Shares against payment therefor in accordance
with the terms of the Plan and any agreement thereunder, the Registered Shares
will be legally issued, fully paid and non-assessable shares of the Company's
Common Stock under the General Corporation Law of the State of Delaware.

         The foregoing assumes all requisite steps will be taken to comply with
the requirements of the Act, applicable requirements of state laws regulating
the offer and sale of securities and applicable requirements of The Nasdaq Stock
Market, Inc.

         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