Introduction: The association between gastroesophageal reflux disease (GERD) and morbidity and mortality in patients with pulmonary arterial hypertension (PH) is unknown. Our objective was to examine the difference in socio-demographics, comorbidities, and morbidity/mortality in PH patients also diagnosed with GERD, compared to PH patients without GERD.Methods: We performed a retrospective cross-sectional study of the large U.S. National Inpatient Sample identifying patients with a primary diagnosis of primary pulmonary hypertension (PH). All patients ≥ 18 years old that were admitted with a primary diagnosis of PH from January 1, 2001, to December 31, 2013, in the NIS database were included. We analyzed the socio-demographic and clinical comorbidities in PH patients with and without GERD. We investigated the predictors for complications of PH and differences in hospital utilization in this population.Results: PH patients with GERD were more likely to be older than 18-29 years. They were more likely to be Caucasian and female and less likely to be part of the top 75% median income compared to the bottom 25%. Patients with GERD were more likely insured with Medicare or private insurance but less likely to have Medicaid or be uninsured. Patients were more likely to be obese, and have asthma, chronic bronchitis, obstructive sleep apnea, hypertension, and hypothyroidism but were less likely to have diabetes or a history of alcohol use. PH Patients with GERD were less likely to have myocardial infarctions, cardiac arrests, pulmonary embolisms, pulmonary hemorrhages, cardiac interventions, acute respiratory failure, acute renal failure, or urinary tract infections compared to those without GERD. Patients with GERD were, however, more likely to have acute heart failure exacerbations and aspiration pneumonia. Patients with a diagnosis of GERD had lower mortality, length of stay (LOS), and hospital costs compared to their counterparts.Conclusions: The concomitant presence of GERD is associated with fewer adverse outcomes in patients with PH. Though it is well understood that treatment of GERD is beneficial for lung disease, the exact role of GERD in PH has not been identified. This study helps characterize the important role appropriately treated GERD may play in preventing morbidity and mortality due to PH.