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 31, 1997
 
Innovasive Devices, Inc.
734 Forest Street
Marlborough, MA 01752-3032
 
Gentlemen:
 
  This opinion is delivered to you in connection with a registration statement
on Form S-3 (the "Registration Statement") to be filed on July 31, 1997, by
Innovasive Devices, Inc. (the "Company") under the Securities Act of 1933, as
amended, for registration under said Act of 1,885,000 shares of Common Stock,
$.0001 par value per share (the "Common Stock") of the Company. Terms not
otherwise defined herein shall be deemed to have the meaning ascribed such
term in the Registration Statement.
 
  In connection with rendering this opinion, we have examined such corporate
records, certificates and other documents as we have considered necessary for
the purposes of this opinion. In such examination, we have assumed the
genuineness of all signatures, the authenticity of all documents submitted to
us as originals, the conformity to the original documents of all documents
submitted to us as copies and the authenticity of the originals of such latter
documents. As to any facts material to our opinion, we have, when relevant
facts were not independently established, relied upon the aforesaid records,
certificates and documents.
 
  Based upon the foregoing, we are of the opinion that the shares of Common
Stock to be sold by the Selling Shareholders are and, when sold by the Selling
Shareholders, will be, legally issued, fully paid and non-assessable.
 
  We hereby consent to be named in the Registration Statement and in any
amendments thereto as counsel for the Company, to the statements with
reference to our firm made in the Registration Statement, and to the filing
and use of this opinion as an exhibit to the Registration Statement.
 
                                          Very truly yours,
 
                                          CHOATE, HALL & STEWART