Follow-up evaluations during the first 3 years of life (at 9, 18, and 36 months) were carried out in infants born to women enrolled in a double-blind, randomized trial to evaluate the efficacy and safety of antenatal dexamethasone administration for the prevention of respiratory distress syndrome. Of 739 infants born to 678 mothers, 93 (12.7%), equally distributed between placebo and steroid groups had died, and 240 (32.5%) were lost to follow-up at the end of 3 years. Weight and height at 18 and 36 months, respectively, were slightly greater in infants in the steroid group. No statistically significant differences were observed between the placebo and steroid groups with regard to head circumference and neurologic abnormalities. The Mental Development Index and the Psychomotor Development Index of the Bayley Scales at 9 and 18 months, and the General Cognitive Index or any subscales of the McCarthy Scales of Children's Abilities at 36 months also indicated comparable development within the two groups. No treatment effect was observed on developmental outcomes in boys or girls, in different racial groups, or in different socioeconomic groups. As might be expected, however, MDI, PDI and GCI were significantly influenced by socioeconomic levels. It is concluded that no detectable growth, physical, motor, or developmental deficiencies within the first 3 years of life can be attributed to antenatal dexamethasone therapy in the mothers just prior to delivery.