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                                                                     EXHIBIT 5.1

                               HALE AND DORR LLP
                               COUNSELLORS AT LAW

                 60 STATE STREET, BOSTON, MASSACHUSETTS  02109
                        617-526-6000 . FAX 617-526-5000


                              November 13, 1998


Nitinol Medical Technologies, Inc.
27 Wormwood Streeet
Boston, MA 02210

     Re:  1998 Stock Incentive Plan

Ladies and Gentlemen:

     This opinion is furnished to you in connection with a Registration
Statement on Form S-8 (the "Registration Statement") to be filed with the
Securities and Exchange Commission (the "Commission") under the Securities Act
of 1933, as amended (the "Securities Act"), for the registration of 800,000
shares of Common Stock, $.001 par value per share (the "Shares"), of Nitinol
Medical Technologies, Inc., a Delaware corporation (the "Company"), issuable
under the Company's 1998 Stock Incentive Plan (the "Plan").

     We have examined the Second Amended and Restated Certificate of
Incorporation and the Amended and Restated By-laws of the Company and originals,
or copies certified to our satisfaction, of all pertinent records of the
meetings of the directors and stockholders of the Company, the Registration
Statement and such other documents relating to the Company as we have deemed
material for the purposes of this opinion.

     In our examination of the foregoing documents, we have assumed the
genuineness of all signatures and the authenticity of all documents submitted to
us as originals, the conformity to original documents of all documents submitted
to us as copies, the authenticity of the originals of such latter documents and
the legal competence of all signatories to such documents.

     We express no opinion herein as to the laws of any state or jurisdiction
other than the state laws of the Commonwealth of Massachusetts, the Delaware
General Corporation Law statute and the federal laws of the United States of
America.

     Based upon and subject to the foregoing, we are of the opinion that the
Company has duly authorized for issuance the Shares, and the Shares, when issued
and paid for in accordance with the terms of the Plan and at a price per share
in excess of the par value per share for such Shares, will be validly issued,
fully-paid and nonassessable.


WASHINGTON, D.C.                 BOSTON, MA                         LONDON, UK*
--------------------------------------------------------------------------------
             HALE AND DORR LLP INCLUDES PROFESSIONAL CORPORATIONS
 *BROBECK HALE AND DORR INTERNATIONAL (AN INDEPENDENT JOINT VENTURE LAW FIRM)
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Nitinol Medical Technologies, Inc.
November 13, 1998
Page 2



     It is understood that this opinion is to be used only in connection with
the offer and sale of the Shares while the Registration Statement is in effect.

     This opinion is based upon currently existing statutes, rules, regulations
and judicial decisions, and we disclaim any obligation to advise you of any
change in any of these sources of law or subsequent legal or factual
developments which might affect any matters or opinions set forth herein.

     Please note that we are opining only as to the matters expressly set forth
herein, and no opinion should be inferred as to any other matters.

     We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act.  In giving such
consent, we do not hereby admit that we are in the category of persons whose
consent is required under Section 7 of the Securities Act or the rules and
regulations of the Commission.

                                                Very truly yours,



                                                HALE AND DORR LLP