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                                                                     EXHIBIT 5.1



                                 August 11, 1998

Vicor Corporation
23 Frontage Road
Andover, Massachusetts  01810


         Re:  VICOR CORPORATION -
              REGISTRATION STATEMENT ON FORM S-8


Ladies and Gentlemen:

         This opinion is furnished in connection with the registration pursuant
to the Securities Act of 1933, as amended (the "Act"), of 2,000,000 shares (the
"Shares") of common stock, par value $.01 per share (the "Common Stock"), of
Vicor Corporation (the "Company") which may be issued pursuant to the Vicor
Corporation 1998 Stock Option and Incentive Plan (the "Plan").

         We have acted as counsel to the Company in connection with the
registration of the sale of the Shares under the Act. We have examined the Plan,
the Amended and Restated Certificate of Incorporation and the Amended and
Restated By-laws of the Company; such records of the corporate proceedings of
the Company as we deemed material; and such other certificates, receipts,
records and documents as we considered necessary 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 the general corporation laws of the State of Delaware.

         Based upon the foregoing, we are of the opinion that upon the issuance
and delivery of the Shares, and the receipt of full consideration therefor, in
accordance with the terms of the Registration Statement and the Plan, the Shares
will be legally issued, fully paid and non-assessable shares of the Company's
Common Stock.

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

         We hereby consent to the filing of this opinion as part of the
above-referenced Registration Statement and to the use of our name therein.



                                               Very truly yours,

                                               /s/ Goodwin, Procter & Hoar  LLP

                                               GOODWIN, PROCTER & HOAR  LLP



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