Developmental disabilities have been reported in infants with persistent pulmonary hypertension of the newborn (PPHN) treated with inhaled nitric oxide (INO) or intravenous magnesium sulphate (MgSO(4)) and/or extracorporeal membrane oxygenation. This paper reports the rate of developmental disabilities at 2 years of age in a cohort of survivors of PPHN treated with INO, MgSO(4), or both during the neonatal period.