To learn whether US obstetricians and pediatricians accurately estimate rates of survival and freedom from handicap in preterm infants and to learn whether their knowledge and attitudes influence their choice of interventions that may enhance survival. A cross-sectional survey of obstetricians and pediatricians practicing in the United States was performed using a pretested questionnaire designed to identify their knowledge regarding survival and handicap-free rates of infants born at 23 to 36 weeks of gestation. At each week of gestation, they were asked whether they would provide specific therapeutic interventions to either the expectant mother or infant. Survival and handicap-free rates were compared with published national rates. Obstetricians and pediatricians were divided into an optimists group and a pessimists group, based on their estimates of survival. The rates at which each group used therapeutic interventions were compared. Both obstetricians and pediatricians underestimated survival rates from 24 through 35 weeks of gestation and freedom from serious handicap from 23 through 36 weeks of gestation. On the average, optimists accurately predicted neonatal survival. Obstetricians who underestimated neonatal survival would less often administer antenatal corticosteroids, perform a cesarean section for fetal distress, and transfer a mother to a tertiary center. Pediatricians who underestimated neonatal survival would less often use mechanical ventilation, cardiopulmonary resuscitation, inotropes, intravenous fluids, thermal support, and oxygen supplementation. Physicians underestimate survival and freedom from handicap in preterm infants. Underestimation of outcome is associated with restriction in the use of appropriate interventions.