Seventy-one cases of persistent pulmonary hypertension of the newborn have been reviewed in an attempt to identify possibly preventable causes. Three groups of infants were identified. The first group consisted of 36 infants with evidence of perinatal asphyxia. The second group was made up of 23 infants who exhibited a variety of associated factors including pneumonia, septic shock, and congenital diaphragmatic hernia. A third group included 12 infants delivered by elective repeat cesarean section. Infants in the third group did not have evidence of perinatal asphyxia, meconium aspiration, or infection. Chest roentgenograms revealed amniotic fluid aspiration in seven cases, retained lung fluid in three cases, and normal findings in two cases. All 12 infants in the third group developed respiratory distress which eventually progressed to respiratory failure and persistent pulmonary hypertension of the newborn. These data suggest that infants of elective repeat cesarean deliveries are at risk for developing persistent pulmonary hypertension of the newborn and constitute a group of patients with a potentially preventable course of events.