BACKGROUND: Few studies have prospectively reported outcomes in patients with pulmonary arterial hypertension (PAH) treated with epoprostenol in the modern-day era of oral therapy and combination treatments. The Registry to Prospectively Describe Use of Epoprostenol for Injection (Veletri, prolonged room temperature stable-epoprostenol [RTS-Epo]) in Patients with Pulmonary Arterial Hypertension (PROSPECT) was established to prospectively describe the course of PAH in patients prescribed RTS-Epo. METHODS: PROSPECT is a multicenter, US-based drug registry of primarily group 1 patients with PAH treated with RTS-Epo who were parenteral-naive or parenteral-transitioned at enrollment. Patients were followed until discontinuation of RTS-Epo, withdrawal, loss to follow-up, death, or end of study (maximum 1 year). One-year freedom from hospitalization (FH) and survival estimates were summarized by prostacyclin history (parenteral-naive or parenteral-transitioned), sex, and chronic renal insufficiency (CRI). RESULTS: A total of 336 patients were included. The overall 1-year FH estimate was 51.0% ± 2.8% and was lower in parenteral-naive patients than parenteral-transitioned patients (42.8% ± 4.3% vs 57.1% ± 3.7%, respectively; P = .002). FH estimates were lower in male patients than female patients (38.3% ± 5.9% vs 54.6% ± 3.2%, respectively; P < .015) and in patients with CRI than patients without CRI (17.0% ± 8.4% vs 53.7% ± 2.9%, respectively; P < .001). The overall 1-year survival estimate was 84.0% ± 2.1%. Survival was poorer in parenteral-naive patients, male patients, and patients with CRI. CONCLUSIONS: Risk of hospitalization and mortality remain high in patients with PAH. In particular, patients who are parenteral-naive at initiation of RTS-Epo therapy, male patients, and patients with CRI require close monitoring and aggressive clinical management.