POWER OF ATTORNEY
Know all by these presents, that the undersigned, as a Section 16 reporting person of Medidata
Solutions, Inc. (the "Company"), hereby constitutes and appoints each of Cory Douglas, Michael
I. Otner and Kathryn Schneider, signing singly, the undersigned's true and lawful attorney-in-fact
to:
(1) prepare, execute in the undersigned's name and on the undersigned's behalf,
and submit to the U.S. Securities and Exchange Commission (the "SEC")
amendments to Form ID and any other documents necessary or appropriate to
maintain codes and passwords enabling the undersigned to make electronic filings
with the SEC of reports required by Section 16(a) of the Securities Exchange Act of
1934 or any rule or regulation of the SEC;
(2) execute for and on behalf of the undersigned, as a Section 16 reporting person
of the Company, Forms 3, 4, and 5 in accordance with Section 16(a) of the
Securities Exchange Act of 1934 and the rules thereunder, and any other forms or
reports the undersigned may be required to file in connection with the undersigned's
ownership, acquisition, or disposition of securities of the Company;
(3) do and perform any and all acts for and on behalf of the undersigned which
may be necessary or desirable to complete and execute any such Form 3, 4, or 5, or
other form or report, and timely file such form or report with the SEC and any stock
exchange or similar authority; and
(4) take any other action of any type whatsoever in connection with the foregoing
which, in the opinion of such attorney-in-fact, may be of benefit to, in the best
interest of, or legally required by, the undersigned, it being understood that the
documents executed by such attorney-in-fact on behalf of the undersigned pursuant
to this Power of Attorney shall be in such form and shall contain such terms and
conditions as such attorney-in-fact may approve in such attorney-in-fact's
discretion.
       The undersigned hereby grants to each such attorney-in-fact full power and authority to do
and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in
the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as
the undersigned might or could do if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that such attorney-in-fact, or such attorney-in-fact's
substitute or substitutes, shall lawfully do or cause to be done by virtue of this Power of Attorney
and the rights and powers herein granted.  The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming,
nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16
of the Securities Exchange Act of 1934.
       This Power of Attorney shall remain in full force and effect until the undersigned is no
longer required to file Forms 3, 4, and 5 with respect to the undersigned's holdings of and
transactions in securities issued by the Company, unless earlier revoked by the undersigned in a
signed writing delivered to the foregoing attorneys-in-fact.
       IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 1st day of July, 2014.

       					Signature:	 /s/ DAVID COLISTRA

       					Print Name:	David Colistra

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