POWER OF ATTORNEY

      KNOW ALL PERSONS BY THESE PRESENTS, that the
undersigned, R. Paul Gray, hereby makes, constitutes and
appoints each of Paul A. Mahon, Andrew Fisher, John S. Hess,
Jr. and Christopher Stillabower, or each of them acting
individually, as the undersigned's true and lawful agent and
attorney-in-fact with full power and authority to:

(1)	execute, deliver and file with the United States
Securities and Exchange Commission on behalf of the
undersigned in the undersigned's capacity as a director and/or
officer of United Therapeutics Corporation (the "Company"),
all Forms 3, 4 and 5, and any amendments thereto (together,
the "Documents"), as may be required in accordance with
Section 16(a) of the Securities Exchange Act of 1934 and the
rules and regulations promulgated thereunder;

(2)	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 Documents, and timely file any such
Document with the United States Securities and Exchange
Commission and any stock exchange or similar authority; and

(3)	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 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.  Each of the attorneys-in-
fact named herein shall have the power to act hereunder with
or without the other.  The undersigned acknowledges that the
attorneys-in-fact named herein, in serving in such capacity at
the request of the undersigned, are not assuming, nor is the
Company assuming, any of the undersigned responsibilities to
comply with Section 1 of the Securities Exchange Act of 1934.

      Execution of this Power of Attorney revokes all previous
powers of attorney granted concerning substantially the same
subject matters addressed herein, but does not revoke any
prior power of attorney executed by the undersigned concerning
unrelated matters.  This power of attorney shall not be
revoked by any subsequent power of attorney the undersigned
may execute, unless such subsequent power specifically refers
to this power of attorney or specifically states that the
instrument is intended to revoke all prior general powers of
attorney or all prior powers of attorney.

      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.  This Power of
Attorney shall be automatically revoked against any of the
foregoing attorneys-in-fact upon the termination of such
person's employment with the Company, which revocation shall
not impact the power of attorney granted hereby to each of the
other attorneys-in-fact who remain employed by the Company.

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IN WITNESS WHEREOF, the undersigned has caused this Power of
Attorney to be executed as of the 8th day of November, 2010.

/s/ R. Paul Gray
 R. Paul Gray

ACKNOWLEDGEMENT

STATE OF MARYLAND

      On this 8th day of November, 2010, before me the
undersigned, personally appeared R. Paul Gray, personally
known to be or proved to me on the basis of satisfactory
evidence to be the individual whose name is subscribed to the
within instrument and acknowledged to me that he executed the
same in his capacity, and that by his signature on the
instrument, the individual, or the person who acted on behalf
of the individual, executed the instrument and that such
individual made such appearance before the undersigned.

/s/ Nancy I. Rivera
 Notary

SUBSCRIBED AND SWORN TO BEFORE ME IN MY PRESENCE THIS 8th DAY
OF NOV, 2010.  A NOTARY PUBLIC IN AND FOR THE STATE OF
MARYLAND, NANCY I. RIVERA.  MY COMMISSION EXPIRES MARCH 24,
2012.