OBJECTIVES: Selexipag is an oral selective prostacyclin IP receptor agonist indicated in the US for the treatment of pulmonary arterial hypertension (PAH) to delay disease progression and reduce the risk of hospitalization for PAH. The objective of the analysis was to estimate the potential budget impact of introducing selexipag for a hypothetical US health plan.   METHODS: An Excel-based budget impact model assuming 1,000,000 hypothetical plan members and a two-year time horizon was developed. Annual total costs of treatment were calculated and compared for two scenarios: with and without selexipag. The proportion of patients diagnosed with PAH and currently treated with drugs acting on the prostacyclin pathway was based on published epidemiology literature and market research data. Selexipag is projected to partially replace inhaled iloprost, and oral/inhaled treprostinil in patients naïve to drugs acting on the prostacyclin pathway. Drug costs were derived from 2015 wholesale acquisition costs. Incidence of adverse events, adverse event treatment costs, and drug administration costs were taken from published literature. Rebates and discounting of future costs were not considered. A one way sensitivity analysis varying model parameters was conducted.   RESULTS: In this hypothetical plan of 1,000,000 members, the number of PAH patients using drugs acting on the prostacyclin pathway was projected to be 22 and 23 in year one and two, respectively. The expected 2-year total cost was offset by 15% with the introduction of selexipag, corresponding to a cost saving of $0.04 per member per month (PMPM), after the introduction of selexipag. Sensitivity analyses showed that the results are most influenced by the projected market shares of inhaled, parenteral and oral treprostinil. CONCLUSIONS: The adoption of selexipag as a treatment option for PAH may result in budget savings. Due to the rarity of PAH, the overall PMPM impact to a health plan is likely to be budget neutral.