Objective. To determine the feasibility of administering iloprost by inhalation in patients with mild atopic asthma. Methods. Volunteers underwent supervised inhalation of iloprost in the clinic with measurement of spirometry and blood pressure for 2 hours. The volunteers then inhaled iloprost four times daily at a dose of 2.5 or 5 μg for 14 days. Spirometry, asthma questionnaires, peak flow diaries, measurement of methacholine responsiveness, and exhaled nitric oxide concentrations were obtained prior to and after the treatment period. Results. Chronic inhalation of iloprost (2.5–5 μg) did not alter spirometry or methacholine responsiveness. Conclusion. Inhaled iloprost in carefully selected volunteers with mild asthma appears to be a suitable intervention to explore the effects of prostacyclin in human asthma.