We conducted a randomized, double-blind, controlled trial to determine whether vitamin A supplementation from early postnatal life could reduce the morbidity associated with bronchopulmonary dysplasia in very low birth weight (VLBW) neonates. Forty VLBW neonates (700 to 1300 g birth weight, 26 to 30 weeks gestational age), who were oxygen dependent and required mechanical ventilation for at least 72 hours after birth, were given by the intramuscular route either supplemental vitamin A (retinyl palmitate 2000 IU) or 0.9% saline solution on postnatal day 4 and every other day thereafter for a total of 14 injections over 28 days. The study groups were comparable in gestational maturity, clinical characteristics, initial lung disease, and vitamin A status at entry into the trial. Vitamin A administration resulted in significantly higher mean plasma concentrations of vitamin A and retinol-binding protein in treated infants compared with controls. Bronchopulmonary dysplasia was diagnosed in nine of 20 infants given vitamin A supplement and in 17 of 20 control infants (P less than 0.008). Four of 19 infants in the vitamin A group and 11 of 20 in the control group required mechanical ventilation on study day 28 (P less than 0.029). The need for supplemental oxygen, mechanical ventilation, and intensive care was reduced in infants given vitamin A supplement compared with controls. Airway infection and retinopathy of prematurity were less frequent in the vitamin A group. We conclude that vitamin A supplementation at the dosage used in this trial in VLBW neonates not only improves their vitamin A status but also appears to promote regenerative healing from lung injury, as evidenced by a decrease in the morbidity associated with bronchopulmonary dysplasia.