Infants with birth weights from 401-1000g and who received mechanical ventilation or supplemental oxygen at 24-96 hours of age were enrolled. Subjects were randomized to either the vitamin A or a control group. Infants in the Vitamin A group were given a dose of 5000 IU (0.1 ml) intramuscularly on Mondays, Wednesdays, and Fridays for four weeks. Control infants received a sham procedure rather than placebo injections.