PURPOSE Data on early pulmonary arterial hypertension (PAH) in preterm infants is limited and outcomes are conflicting. Our objectives are to examine the risk factors and neonatal outcomes of early onset PAH (EOPAH) diagnosed in the first 2 weeks of age in preterm infants in a large perinatal center. METHODS We performed a case-control study to assess the risk factors and clinical outcomes of preterm infants with EOPAH. Preterm infants (<34 weeks) admitted to NICU between 2009 and 2013 with a diagnosis of PAH in the first 2 weeks of age were matched to two consecutive controls for gestational age, birth weight, and year of birth. We performed univariate and multivariate analyses. RESULTS Of 1798 eligible infants, 60 (3.3%) had EOPAH with 57/60 (95%) diagnosed in the first 7 d of age. Infants with early PAH had higher incidence of prolonged rupture of membrane (47% versus 29%), oligohydramnios (37% versus 16%) and received less antenatal steroids (78% versus 91%). Fifty-one infants received inhaled nitric oxide (iNO) and all responded well. The overall mortality rate was not significantly different between two groups (13.3% versus 8%). After adjusting for potential confounding variables, early PAH is associated with bronchopulmonary dysplasia (BPD) (aOR 3.06, 95% CI 1.43, 6.54) and BPD/death (aOR 2.65, 95% CI 1.25, 5.64) and severe intraventricular hemorrhage (aOR 3.08, 95% CI 1.28, 7.39). CONCLUSION Early onset pulmonary arterial hypertension in preterm is not uncommon and is associated with bronchopulmonary dysplasia and severe intraventricular hemorrhage. Inhaled nitric oxide was used to treat in majority of cases with good response and survival is high.