Critically ill premature infants requiring mechanical ventilation and an umbilical artery catheter usually do not receive enteral feedings during the acute phase of their illness. We studied the safety and benefit of early minimal enteral feedings during this time in a prospective, controlled, and randomized study. Twenty-nine infants were randomly assigned to receive only standard intravenous fluid and nutrition (nothing per OS, NPO group; n = 13), or in addition to receive small-volume hypocaloric continuous feedings (1 ml/kg/h), beginning at 24 h of age (early-feeding group; n = 16). Standard enteral feedings were begun in both groups at the resolution of the acute phase of the illness and advanced by protocol. The two groups were of comparable birth weight, gestational age, and Apgar scores. There were no significant differences in the episodes of feeding intolerance. Two infants in the NPO group developed clinical signs of necrotizing enterocolitis. Serum diamine oxidase and somatomedin C were measured weekly until 30-60 days of age and were not different between the two groups. The early-feeding group required fewer days to reach 120 ml/kg/day enteral intake (early-feeding group 10 +/- 3 days, NPO group 13 +/- 4 days; p < 0.05). On day 30 of life the early-feeding group was 223 +/- 125 g above birth weight, while the NPO group was 95 +/- 161 g above birth weight (p < 0.05). The average intake (kcal/kg/day) from day 6 to day 30 was not different between the two groups. We conclude that early minimal feedings in critically ill very-low-birth-weight infants requiring mechanical ventilation are well tolerated and result in reduced time to reach 120 ml/kg/day of enteral feeding and in a greater weight gain by day 30 of life.