To determine the incidence and risk factors for neonatal hypertension we studied the entire population of 3179 infants admitted to our neonatal intensive care unit over a 6-year period. We report a 0.81% (26/3179) incidence of hypertension in this population. In 13 patients (50%) the hypertension was renal in origin. In four patients (15.4%), the etiology of hypertension could not be determined. Significant risk factors for neonatal hypertension included: bronchopulmonary dysplasia (5.9% in affected infants v 0.5% in unaffected infants, P less than .001); patent ductus arteriosus (3.07% in affected v 0.5% in unaffected infants, P less than .001); intraventricular hemorrhage (2.89% in affected infants v 0.56% in unaffected infants, P less than .001); and umbilical arterial catheterization (8.8% v 0.2% in infants with and without catheterization, respectively, P less than .001).