Thirty-two neonates weighing 500-1500 g with documented surfactant deficiency and without evidence of severe birth asphyxia, infection, prolonged rupture of membranes greater than or equal to 72 h, or oligohydramnios were randomly assigned to receive a single intratracheal dose of surfactant-TA (100 mg/kg) either within 30 min of birth (n = 16, early group) or at 6 h of age (n = 16, late group). By 6 h of age, all neonates of the late group had moderate/severe RDS, while none of the neonates of the early group had either clinical or radiological respiratory distress syndrome. The incidence of bronchopulmonary dysplasia was significantly lower in survivors of the early group than those of the late group (1/15 versus 7/14, a 43% reduction with a 95% confidence interval of 14-72%, P = 0.025). These beneficial effects of early surfactant treatment remained after controlling for the various confounding factors in the logistic models.