OBJECTIVES: Pulmonary arterial hypertension (PAH) is a progressive disease resulting in high healthcare resource use and costs. The objective of this study was to estimate the burden of illness in PAH patients. METHODS: Data came from a large commercial claims database.  PAH patients were identified based on having >2 medical claims for primary pulmonary hypertension (ICD-9 code:416.0), and either one claim for right heart catheterization or one claim of echocardiogram and diagnosed by a pulmonologist/cardiologist within 12 months of the medical claim. The first medical claim during this period served as in the index date with 12 months prior to this event as baseline and 12 months post as follow-up period.  Demographic variables were extracted at a patient level from administrative files and economic variables, which included healthcare utilization and costs for outpatient, inpatient, emergency and pharmacy services came from the respective medical and pharmacy claim files and summarized at a per-patient-per-month (PPPM).  Five controls were randomly picked and matched to each PAH patient on demographic characteristics.  Incremental burden of PAH was estimated using non-parametric statistical tests between controls and PAH group.  All costs were adjusted to 2012 base year using consumer price index. RESULTS: 2,245 PAH patients were identified and matched to 11,225 controls.  PAH group had significantly higher (p<0.001) PPPM healthcare utilization compared to the matched control across all drivers: outpatient (2.6 vs. 1.5), inpatient (0.08 vs. 0.02), emergency room (0.1 vs. 0.04), and pharmacy services (4.2 vs. 2.6). The increase in utilization translated in higher (p<0.001) total PPPM incremental costs of $3,193 in the PAH group with inpatient ($1,665 vs. $345) and pharmacy costs ($790 vs. $178) being as much as five times greater compared to controls.  CONCLUSIONS: Healthcare resource use and costs for PAH patients is high from a managed care perspective.