EXHIBIT 5.1
                                                                     -----------


                             CHOATE, HALL & STEWART
               A PARTNERSHIP INCLUDING PROFESSIONAL CORPORATIONS
                                 EXCHANGE PLACE
                                53 STATE STREET
                       BOSTON, MASSACHUSETTS  02109-2891
                            TELEPHONE (617) 248-5000
                            FACSIMILE (617) 248-4000
                                 TELEX 49615860


                                         July 21, 1999


Innovasive Devices, Inc.
734 Forest Street
Marlborough, Massachusetts 01752-3032

Gentlemen:

     This opinion is delivered to you in connection with the registration
statement on Form S-8 (the "Registration Statement") to be filed on July 21,
1999 by Innovasive Devices, Inc. (the "Company") under the Securities Act of
1933, as amended, for registration under said Act of 100,000 shares of common
stock, $.0001 par value (the "Common Stock"), of the Company.

     We are familiar with the Company's Third Restated Articles of Organization,
as amended, its By-Laws, as amended, and its corporate minute book as well as
the Registration Statement.  We have also examined such other documents, records
and certificates and made such further investigation as we have deemed necessary
for the purposes of this opinion.

     Based upon and subject to the foregoing, we are of the opinion that the
shares of Common Stock to be sold by the Company under its 1996 Employee Stock
Purchase Plan, as in effect on the date hereof, when issued against receipt of
the agreed purchase price therefor, will be legally issued, fully paid and
nonassessable.

     We understand that this opinion is to be used in connection with the
Registration Statement and consent to the filing of this opinion as an exhibit
to the Registration Statement.  We further consent to the reference to this firm
in the section entitled "Interests of Named Experts and Counsel" in the
Registration Statement.

                                    Very truly yours,


                                    CHOATE, HALL & STEWART