CORPORATE HEADQUARTERS

1040 Spring Street

Silver Spring, Maryland 20910

Tel. (301) 608-9292

Fax. (301) 608-9291

RESEARCH AND DEVELOPMENT

55 T.W. Alexander Drive

P.O. Box 14186

Research Triangle Park, North Carolina 27709

Tel. (919) 485-8350

Fax. (919) 485-8352

LEGAL AND GOVERNMENTAL AFFAIRS

1735 Connecticut Avenue N.W.

Washington, D.C. 20009

Tel. (202) 483-7000

Fax. (202) 483-4005

OPERATING SUBSIDIARIES

Medicomp, Inc.

7845 Ellis Road

Melbourne, Florida 32904

Tel. (321) 676-0010

Fax. (321) 676-2282

www.medicompinc.com

Lung Rx, Inc.

1104 Spring Street

Silver Spring, MD 20910

Phone: (301) 608-9292

Fax: (301) 608-1139

www.lungrx.com

United Therapeutics Europe, Ltd.

Unither House

Curfew Bell Road

Chertsey, Surrey KT16 9FG

United Kingdom

Tel. +44 (0)1932 573800

Fax. +44 (0)1932 571110

Unither Biothèque Inc.

101, rue Du Moulin bureau 202-B

Magog, Quebec J1X 4A1

Canada

Tel. (819) 843-9138

Fax. (819) 843-4287

Unither Virology, LLC

1733 Connecticut Avenue N.W.

Washington, DC 20009

Tel. (202) 986-2342

Fax. (202) 986-234

Unither Neurosciences, Inc.

82 Pearl Street

Burlington, VT 05402

Tel. (802) 651-0147

Fax. (802) 651-1057

Unither Therapeutik GmbH

GmbH Kreuzfeldring 17

63820 Elsenfeld

Germany

Tel.: (+49) (0) 6022 50894 0

Fax: (+49) (0) 6022-610 6299

TRANSFER  AGENT AND REGISTRAR

BNY Mellon Shareowner Services

480Washington Boulevard

Jersey City, New Jersey 07310

(800) 522-6645

From outside the US and Canada:

(201) 680-6578

TDD: (800) 231-5469

http://www.bnymellon.com/shareowner/isd

ATTORNEYS

Gibson Dunn & Crutcher LLP

1050 Connecticut Avenue N.W.

Washington, D.C. 20036

Tel: (202) 955-8500

Fax: (202) 467-0539

AUDITORS

Ernst & Young LLP

8484Westpark Drive

McLean, Virginia 22102

Tel. (703) 747-1000

Fax. (703) 747-0100

COMMON STOCK

Listed on the NASDAQ Global Select

Market under trading symbol "UTHR"

CORPORATE WEBSITE

www.unither.com