OBJECTIVE To review the pharmacology, pharmacodynamics, and clinical trials evaluating inhaled iloprost in pulmonary arterial hypertension (PAH). DATA SOURCES A MEDLINE search (1996–February 2005) was performed using the key words pulmonary hypertension, iloprost, and epoprostenol. Information regarding Food and Drug Administration approval was obtained via the Internet. STUDY SELECTION AND DATA EXTRACTION All clinical trials using inhaled iloprost in PAH published in English were identified. Additionally, references from the identified articles were reviewed. DATA SYNTHESIS A stable analog of prostacyclin, inhaled iloprost is thought to promote benefit in PAH through vasodilation, antiproliferative effects, and inhibition of platelet aggregation. In a placebo-controlled trial of 203 patients, inhaled iloprost significantly improved the combined endpoint of change in New York Heart Association functional class and 10% improvement in 6-minute walk distance (p = 0.007). Small, short-term clinical trials demonstrated hemodynamic benefits for inhaled iloprost alone and in combination with other pulmonary vasodilating agents. The aerosolized delivery route and low incidence of adverse events are positive attributes for inhaled iloprost, while the frequency of administration and lack of comparative data limit its role in PAH. CONCLUSIONS Currently, inhaled iloprost offers potential benefit for patients with contraindications to bosentan, preference for non-parenteral products, ineligibility for parenteral therapy, or as adjunctive therapy with other pulmonary vasodilators. Larger, long-term clinical trials are needed to solidify the role for inhaled iloprost in the management of PAH.