OBJECTIVE To review briefly the epidemiology, pathophysiology, and current treatment of primary pulmonary hypertension (PPH) and review the available clinical data on epoprostenol in PPH. METHODS A MEDLINE search (January 1966-August 1998) was used to identify case reports and clinical studies pertaining to epoprostenol in PPH. Bibliographic lists were also used. METHODS All English-language clinical studies of epoprostenol in PPH were included. Incomplete study descriptions (abstracts) were not included. METHODS Study design, population, methods, clinical outcomes, and adverse effects were evaluated. RESULTS PPH is a relatively rare disease that results in symptoms of congestive heart failure and has a five-year survival rate of 34%. Therapy has consisted of vasodilators, anticoagulation, oxygen, and ultimately lung transplantation. Epoprostenol, which has recently become available as an integral pharmacotherapeutic option, has been shown to improve hemodynamic parameters such as cardiac output, pulmonary artery pressure, and pulmonary vascular resistance. It has been shown to improve exercise parameters, New York Heart Association (NYHA) functional class, and survival. Epoprostenol is indicated for patients with severe disease (NYHA class III or IV) who do not respond to acute vasodilator challenge or chronic calcium-channel blocker therapy. Its chronic administration is challenging as it requires continuous infusion via central venous catheter and a special infusion pump. Administration is further complicated by the 48-hour expiration of reconstituted epoprostenol and the need to refrigerate the reconstituted drug. CONCLUSIONS Epoprostenol improves hemodynamics and clinical outcome in patients with severe PPH. Epoprostenol therapy requires intensive patient education and medical monitoring, but it can improve well-being and delay the need for lung transplantation.