A three-dose prophylactic regimen of synthetic surfactant replacement has been shown to improve neonatal and 1-year survival rates in infants of 700 to 1100 gm birth weight when compared with a single prophylactic dose. The purpose of this study was to evaluate the growth, development, and late morbidity at 1 year adjusted age among the survivors of the 826 patients enrolled in the protocol. Complete follow-up data were obtained for 75% of the survivors in both groups. Chronic lung disease, need for respiratory support, neurologic disease requiring medication, visual or auditory impairments, and the incidence and severity of retinopathy of prematurity were equivalent in the two groups. The frequency of neurodevelopmental impairment was also comparable in the groups that received one dose versus three doses: moderate to severe cerebral palsy was found in 9% versus 6%, mental retardation assessed by Bayley Scales of Infant Development scores less than 69 was found in 16% vs 14%, and moderate to severe impairments of any kind were found in 33% vs 24%, respectively. Furthermore, the absolute number of impaired survivors was 92 in the three-dose group versus 106 in the one-dose group, despite a higher survival rate in the three-dose group. This study demonstrates that developmental outcomes of infants weighing 700 to 1100 gm who received three prophylactic doses of synthetic surfactant are at least as good as those of infants receiving a single dose, and that improving survival rates of very premature infants with synthetic surfactant does not result in increased numbers of infants with impairments.