Exhibit 5.1

                                 July 19, 2000


Equinix, Inc.
901 Marshall Street
Redwood City, CA 94063


     Re:  Registration Statement on Form S-1
          ----------------------------------

Ladies and Gentlemen:

     We have examined the Registration Statement on Form S-1 (File No. 333-
39752) originally filed by Equinix, Inc. (the "Company") with the Securities and
Exchange Commission (the "Commission") on June 21, 2000, as thereafter amended
or supplemented (the "Registration Statement"), in connection with the
registration under the Securities Act of 1933, as amended, of up to 23,000,000
shares of the Company's Common Stock (the "Shares").  The Shares, which include
an over-allotment option granted by the Company to the Underwriters to purchase
up to 3,000,000 additional shares of the Company's Common Stock, are to be sold
to the Underwriters by the Company as described in the Registration Statement
for resale to the public.  As your counsel in connection with this transaction,
we have examined the proceedings taken and are familiar with the proceedings
proposed to be taken by you in connection with the sale and issuance of the
Shares.

     It is our opinion that, upon completion of the proceedings being taken in
order to permit such transactions to be carried out in accordance with the
securities laws of the various states where required, the Shares being sold by
the Company, when issued and sold in the manner described in the Registration
Statement and in accordance with the resolutions adopted by the Board of
Directors of the Company, will be legally and validly issued, fully paid and
non-assessable.

     We consent to the use of this opinion as an exhibit to said Registration
Statement and further consent to the use of our name wherever appearing in said
Registration Statement, including the prospectus constituting a part thereof,
and in any amendment or supplement thereto.

                         Very truly yours,

                         /s/ GUNDERSON DETTMER STOUGH
                             VILLENEUVE FRANKLIN & HACHIGIAN, LLP

                         Gunderson Dettmer Stough
                         Villeneuve Franklin & Hachigian, LLP