UNITED THERAPEUTICSCORPORATION SUPPLEMENTAL EXECUTIVE RETIREMENTPLAN RABBI TRUST DOCUMENT

notwithstanding Trustee’s receipt of “float” from such uninvested cash, by depositing the same in any bank (including deposits which bear a reasonable rate of interest in a bank or similar financial institution supervised by the United States or a State, even where a bank or financial institution is the Trustee, or is otherwise a fiduciary of the Plan) subject to the rules and regulations governing such deposits, and without regard to the amount of such deposit.  In addition, Trustee is specifically authorized to invest idle, or otherwise uninvested, cash in a money market mutual fund selected by Trustee in its sole discretion, including any money market fund associated with Trustee as described in subparagraph (c) above.

Section 5.  Disposition of Income

                During the term of this Trust, all income received by the Trust, net of expenses and taxes, shall be accumulated and reinvested.

Section 6.  Accounting by Trustee

                Trustee shall keep accurate and detailed records of all investments, receipts, disbursements, and all other transactions required to be made, including such specific records as shall be agreed upon in writing between Company and Trustee.  Within 60 days following the close of each calendar year and within 60 days after the removal or resignation of Trustee, Trustee shall deliver to Company a written account of its administration of the Trust during such year or during the period from the close of the last preceding year to the date of such removal or resignation, setting forth all investments, receipts, disbursements and other transactions effected by it, including a description of all securities and investments purchased and sold with the cost or net proceeds of such purchases or sales (accrued interest paid or receivable being shown separately), and showing all cash, securities and other property held in the Trust at the end of such year or as of the date of such removal or resignation, as the case may be.  In addition, Trustee shall provide the Company a monthly statement including such information.  Such account statements shall be mailed to Company or, if the Company agrees, delivered via e-mail or other electronic means.

Section 7.  Responsibility of Trustee.

                (a)  Trustee shall act with care, skill, prudence and diligence under the circumstances then prevailing that a prudent person acting in like capacity and familiar with such matters would use in the conduct of any enterprise of a like character and with like aims, provided, however, that Trustee shall incur no liability to any person for any action taken pursuant to a direction, request or approval given by Company or an investment manager which is contemplated by, and in conformity with, the terms of the Plan or this Trust and is given in writing by Company or such investment manager.  In the event of a dispute between Company and a party, Trustee may apply to a court of competent jurisdiction to resolve the dispute.

                (b)  If Trustee undertakes or defends any litigation arising in connection with this Trust, Company agrees to indemnify Trustee against Trustee’s costs, expenses and liabilities (including, without limitation, attorneys’ fees and expenses) relating thereto and to be primarily liable for such payments.  If Company does not pay such costs, expenses and liabilities in a reasonably timely manner, Trustee may obtain payment from the Trust.  In no event shall Trustee have any liability or responsibility to undertake, defend or continue any litigation unless payment of related fees and expenses is ensured to the reasonable satisfaction of Trustee.

                (c)  Trustee, at the expense of the Trust or the Company, may consult with legal counsel (who may also be counsel for Company generally) with respect to any of its duties or obligations hereunder provided that Trustee notifies Company in advance (to the extent practicable or if not practicable, as soon as reasonably possible) of incurring such expense.

                (d)  Trustee, at the expense of the Trust or the Company, may hire agents, accountants, actuaries, investment advisors, financial consultants or other professionals to assist it in performing any of its duties or obligations hereunder.

                (e)  Trustee shall have, without exclusion, all powers conferred on trustees by applicable law, unless expressly provided otherwise herein, provided, however, that if an insurance policy is held as an asset of the Trust, Trustee shall have no power to name a beneficiary of the policy other than the Trust, to assign the policy (as distinct from conversion of the policy to a different form) other than to a successor Trustee, or to loan to any person the proceeds of any borrowing against such policy.

                (f)  However, notwithstanding the provisions of Section 7(e) above, Trustee may loan to Company the proceeds of any borrowing against an insurance policy (if any) held as an asset of the Trust.

                (g)  Notwithstanding any powers granted to Trustee pursuant to this Trust Agreement or to applicable law, Trustee shall not have any power that could give this Trust the objective of carrying on a business and dividing the gains therefrom, within the meaning of section ###-###-####-2 of the Procedure and Administrative Regulations promulgated pursuant to the Internal Revenue Code.

                (h)  Trustee shall have no responsibility or liability respect to: (i) the truth or accuracy of any representation or warranty made in any application or related document provided to the insurer in connection with the issuance or renewal of any insurance policies or insurance contracts, including any representation that the person on whose life an application is being made is eligible to have a contract issued on his or her life; (ii) the selection or monitoring (ongoing or periodic) of any insurance policies or insurance contracts held in the Trust or the insurers issuing such policies or contracts; (iii) the payment of premiums with respect to such policies or contracts; or (iv) the exercise of any rights relating to any such policies or contracts except as directed in writing by Company.

                (i)  Upon the expiration of one hundred twenty (120) days from the date of Trustee’s annual, quarterly or any other account, the Trustee shall be forever released and discharged from all liability and further accountability to Company or any other person with respect to the accuracy of such accounting and all acts and failures to act of Trustee reflected in such account, except to the extent that Company shall, within such 120-day period, file with Trustee specific written objections to the account.  Neither Company, any participant nor any other person shall be entitled to any additional or different accounting by Trustee and Trustee shall not be compelled to file in any court any additional or different accounting.  For purposes of regulations promulgated by the FDIC, Trustee’s account statements shall be sufficient information concerning securities transactions effected for the Trust, provided that Company, upon written request, shall have the right to receive at no additional cost written confirmations of such securities transactions, which shall be mailed or otherwise furnished by the Trustee within the timeframe required by applicable regulations.

                (j)  Trustee shall have no duty or responsibility not expressly set forth in this Trust Agreement.  By way of example, but without limiting the matters subject to the foregoing sentence, Trustee shall have no responsibility with respect to the administration or interpretation of the Plan, payment of Plan benefits other than from the assets of the Trust, the calculation of tax to be withheld, reported and/or paid to taxing authorities and (if applicable pursuant to the fee schedule) withholding, remitting, or reporting to taxing authorities of taxes other than from payments made with Trust assets to Plan participants and other than as directed by Company, or maintaining participant records with respect to the Plan.

Section 8.  Compensation and Expenses of Trustee.

                (a)  Company shall pay all administrative and Trustee’s fees and expenses on a monthly basis.  If not so paid, the Trustee shall be entitled to deduct such fees and expenses from the Trust.

                (b)  Company shall indemnify and hold Trustee harmless from and against any and all losses, costs, damages and expenses (including attorney’s fees and disbursements) of any kind or nature (collectively, “Losses”) imposed on or incurred by Trustee by reason of its service pursuant to this Trust Agreement, including any Losses arising out of any threatened, pending or completed claim, action, suit or proceeding, except to the extent such Losses are caused by the gross negligence, willful misconduct or bad faith of Trustee.  To the extent not paid by Company, Trustee shall be entitled to deduct such amounts from the Trust.

                (c)  The provisions of this Section 8 shall survive termination of this Trust Agreement.

Section 9.  Resignation and Removal of Trustee.

                (a)  Trustee may resign at any time by written notice to Company, which shall be effective thirty (30) days after receipt of such notice unless Company and Trustee agree otherwise.

                (b)  Trustee may be removed by Company on thirty (30) days notice or upon shorter notice accepted by Trustee; provided that, following a Change of Control, Trustee may be removed only with the unanimous consent of the participants in the Plan.

                (c)  If Trustee resigns within three (3) years after a Change of Control, as defined herein, Company shall apply to a court of competent jurisdiction for the appointment of a successor Trustee or for instructions.

                (d)  Upon resignation or removal of Trustee and appointment of a successor Trustee, all assets shall subsequently be transferred to the successor Trustee.  To the extent possible, the transfer shall be completed within thirty (30) days after receipt of notice of resignation, removal or transfer, unless Company extends the time limit.

                (e)  If Trustee resigns or is removed, a successor shall be appointed, in accordance with Section 10 hereof, by the effective date of resignation or removal under paragraphs (a) or (b) of this section.  If no such appointment has been made, Trustee may apply to a court of competent jurisdiction for appointment of a successor or for instructions.  All expenses of Trustee in connection with the proceeding shall be allowed as administrative expenses of the Trust.

Section 10.  Appointment of Successor.

                If Trustee resigns or is removed in accordance with Section 9(a) or (b) hereof, Company may appoint any third party, such as a bank trust department or other party that may be granted corporate trustee powers under state law, as a successor to replace Trustee upon resignation or removal.  The appointment shall be effective when accepted in writing by the new Trustee, who shall have all of the rights and powers of the former Trustee, including ownership rights in the Trust assets.  The former Trustee shall execute any instrument necessary or reasonably requested by Company or the successor Trustee to evidence the transfer.

Section 11.  Amendment or Termination.

                (a)  This Trust Agreement may be amended by a written instrument executed by Trustee and Company.  Notwithstanding the foregoing, no such amendment shall conflict with the terms of the Plan or shall make the Trust revocable.  In addition, following a Change of Control, the Trust Agreement may be amended only with the unanimous consent of the participants in the Plan.

                (b)  The Trust shall not terminate until the date on which Plan participants and their beneficiaries are no longer entitled to benefits pursuant to the terms of the Plan.  Upon termination of the Trust any assets remaining in the Trust shall be returned to Company.

Section 12.  Miscellaneous.

                (a)  Any provision of this Trust Agreement prohibited by law shall be ineffective to the extent of any such prohibition, without invalidating the remaining provisions hereof.

                (b)  Benefits payable to Plan participants and their beneficiaries under this Trust Agreement may not be anticipated, assigned (either at law or in equity), alienated, pledged, encumbered or subjected to attachment, garnishment, levy, execution or other legal or equitable process.

                (c)  This Trust Agreement shall be governed by and construed in accordance with the laws of the State of Delaware.

                (d)  Trustee represents that it qualifies for FDIC prorata worth pass-through insurance coverage in accordance with the standards set forth in applicable federal law and FDIC insurance regulations.  If Trustee fails at any time in the future to so qualify for prorata worth pass-through insurance coverage, it will promptly notify Company.

                (e)  In no event will Trustee have any obligation to provide, and in no event will Trustee provide, any legal, tax, accounting, audit or other advice to Company with respect to the Plan or this Trust.  Company acknowledges that it will rely exclusively on the advice of its accountants and/or attorneys with respect to all legal, tax, accounting, audit and other advice required or desired by Company with respect to the Plan or this Trust.  Company acknowledges that Trustee has not made any representations of any kind, and will not make any representations of any kind, concerning the legal, tax, accounting, audit or other treatment of the Plan or this Trust.

                (f)  Company acknowledges that Trustee is not an advisor concerning or a promoter with respect to the Plan or the Trust, but merely is a service provider offering the Trust services expressly set forth in this Agreement.  In particular, Company acknowledges that Trustee is not a joint venture or partner with Company’s accountants, auditors, consultants or with any other party, with respect to the Plan or this Trust, and that Trustee and Company’s accountants, auditors and consultants at all times remain independent parties dealing at arm’s length, and independently, with each other and with Company.

                (g)  Company represents and warrants that the Plan and the administration thereof and the establishment of this Trust comply with applicable law and shall continue to be in compliance therewith.

                (h) Trustee shall have no liability for any losses arising out of delays in performing the services which it renders under this Trust Agreement which result from

events beyond its control, including without limitation, interruption of the business of Trustee due to acts of God, acts of governmental authority, acts of war, riots, civil commotions, insurrections, labor difficulties (including, but not limited to, strikes and other work slippages due to slow-downs), or any action of any courier or utility, mechanical or other malfunction, or electronic interruption; provided in each case that Trustee has implemented reasonable procedures or measures to mitigate the effect of such events.

                (h)  For purposes of this Trust, Change of Control shall mean any transfer of control of the Company by acquisition, merger, hostile takeover or for any other reason whatsoever which also qualifies as a “change in the ownership or effective control of the corporation, or in the ownership of a substantial portion of the assets of the corporation” under Code section 409A(a)(2)(A)(v).: