Exhibit 10.40
Amendment to Employment Agreement between Registrant and Roger Jeffs

AMENDMENT

     THIS AMENDMENT is made as of the 11th day of December, 2002 to the
Employment Agreement between Roger Jeffs, Ph.D. (“Executive”) and United
Therapeutics Corporation dated November 29, 2000 (the “Agreement”).

     WHEREAS, the parties desire to amend the Agreement as provided below.

     NOW THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties hereby amend the
Agreement as follows:

     1.     Waiver of Guaranteed Annual Salary Increase. The first sentence of
Section 4(a) of the Agreement is amended to delete the following language: “,
such annual base salary to be increased by a minimum of 10% on each anniversary
of the term of Executive’s employment hereunder.”

     2.     Effect. No other provisions of the Agreement shall be affected by
this Amendment, and all other provisions of the Agreement shall remain in full
force and effect.

     In witness whereof, the parties have executed this Amendment effective as
of the date first written above.

  UNITED THERAPEUTICS CORPORATION

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Roger Jeffs, Ph.D. Martine Rothblatt, CEO