Primary, or unexplained, pulmonary hypertension is an extremely rare lung disorder. For no apparent reason, blood pressures in the pulmonary artery increase far in excess of normal levels. Prostacycline (Flolan, epoprostenol) has proved effective in the long-term care of patients with Type III or Type IV primary pulmonary hypertension (PPH). These patients require intensive intravenous therapy-related education in the safe and compliant administration of prostacycline. The IV nurse's multiple roles in the care of these patients are clearly delineated: instructor, advocate, and clinical resource specialist.