Background: Prostacyclin have positive effects in improving the cardiopulmonary variables, signs and the hemodynamics of cases with a idiopathic pulmonary artery hypertension (IPAH).The objective of this study was to determine the benefits of intermittent intravenous Iloprost infusion on IPAH cases. Material and Methods: This longitudinal study was conducted on IPAH cases (no=20) at Massih Daneshvari Hospital (2011-2013), treated with cyclic intravenous Iloprost. The treatment consisted of a 6 hours/day Iloprost infusion for three consecutive days. Every 6 weeks the infusion was repeated again with a velocity of 0.5-2.0 ng/kg/min. Before, during and after the completion of functional class, six-minute walk test (6MWD), pulmonary artery pressure (PAP), right ventricular pressure (RVP), and plasma NT-ProBNP level were measured. Result: At follow-up, NYHA score, PAP, RVP, NT-ProBNP and PASP were significantly decreased (P<0.001), while the distance walked in 6MWD was significantly increased. Conclusion: Our results suggest that cyclic intravenous Iloprost might improve the NYHA score, PAP, RVP and can provide a protection against the development or worsening of PAH in patients with IPAH.