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                                                                     EXHIBIT 5.1




                                October 22, 1996




Oacis Healthcare Holdings Corp.
100 Drakes Landing Road, Suite 100
Greenbrae, CA 94904

      RE:  REGISTRATION STATEMENT ON FORM S-8

Ladies and Gentlemen:

         We have examined the Registration Statement on Form S-8 to be filed by
you with the Securities and Exchange Commission on or about October 22, 1996
(the "Registration Statement") in connection with the registration under the
Securities Act of 1933, as amended, of the 1994 Stock Option Plan (as to 685,644
shares), of the 1995 Key Person Stock Plan (as to 726,152 shares), of the 1996
Stock Plan (as to 850,000 shares) of the 1996 Director Option Plan (as to
200,000 shares), and of the 1996 Employee Stock Purchase Plan (as to 250,000
shares) (collectively, the "Plans"). As legal counsel for Oacis Healthcare
Holdings Corp., we have examined the proceedings taken and are familiar with the
proceedings proposed to be taken by you in connection with the issuance and sale
of the Shares pursuant to the Plans.

         It is our opinion that the Shares, when issued and sold in the manner
described in the Plans and pursuant to the agreement that accompanies each grant
under the Plans, will be legally and validly issued, fully-paid and
non-assessable.

         We consent to the use of this opinion as an exhibit to the Registration
Statement, and further consent to the use of our name wherever appearing in the
Registration Statement and any amendments thereto.

                                        Very truly yours,

                                        WILSON SONSINI GOODRICH & ROSATI
                                        Professional Corporation

                                        /S/ WILSON SONSINI GOODRICH & ROSATI