Treprostinil (Remodulin, United Therapeutics) is a stable, long-acting prostacyclin analog, which has been shown to improve clinical state, functional class, exercise capacity and quality of life in patients with pulmonary arterial hypertension, an uncommon disease with poor prognosis. The drug is administered as a continuous subcutaneous infusion using a portable miniature delivery system. Side effects include facial flush, headache, jaw pain, abdominal cramping and diarrhea. These are all typical of prostacyclin impregnation and manageable by symptom-directed dose adjustments. Infusion site pain, a more serious side effect, may limit the treatment in 10% of patients. Otherwise, treprostinil has an excellent safety profile and compares favorably with reference continuous intravenous epoprostenol (Flolan, GlaxoSmithKline) therapy. Treprostinil has a place in currently proposed treatment algorithms of pulmonary arterial hypertension.