EXHIBIT 5.1

                   OPINION OF BROBECK PHLEGER & HARRISON LLP

                                                                 October 3, 2000

GaSonics International Corporation
2730 Junction Avenue
San Jose, California 95134

     Re:  GaSonics International Corporation Registration Statement on Form S-3
          for Resale of 655,577 Shares of Common Stock

Ladies and Gentlemen:

  We have acted as counsel to GaSonics International Corporation, a Delaware
corporation (the "Company"), in connection with the registration for resale of
655,577 shares of the Company's Common Stock (the "Shares"), as described in the
Company's Registration Statement on Form S-3 ("Registration Statement") filed
with the Securities and Exchange Commission under the Securities Act of 1933, as
amended (the "Act").

  This opinion is being furnished in accordance with the requirements of Item 16
of Form S-3 and Item 601(b)(5)(i) of Regulation S-K.

  We have reviewed the Company's charter documents, the corporate proceedings
taken by the Company in connection with the original issuance and sale of the
Shares, and a certificate of a Company officer regarding, among other things,
the Company's receipt of consideration upon the original issuance and sale of
the Shares. Based on such review, we are of the opinion that the Shares are duly
authorized, validly issued, fully paid and nonassessable.

  We consent to the filing of this opinion as Exhibit 5.1 to the Registration
Statement and to the reference to this firm under the caption "Legal Matters" in
the prospectus which is part of the Registration Statement. In giving this
consent, we do not thereby admit that we are within the category of persons
whose consent is required under Section 7 of the Act, the rules and regulations
of the Securities and Exchange Commission promulgated thereunder, or Item 509 of
Regulation S-K.

  This opinion letter is rendered as of the date first written above and we
disclaim any obligation to advise you of facts, circumstances, events or
developments which hereafter may be brought to our attention and which may
alter, affect or modify the opinion expressed herein. Our opinion is expressly
limited to the matters set forth above and we render no opinion, whether by
implication or otherwise, as to any other matters relating to the Company or the
Shares.

                                             Very truly yours,

                                             /s/ Brobeck, Phleger & Harrison LLP


                                             BROBECK, PHLEGER & HARRISON LLP