Plasma concentrations of retinol and retinol-binding protein were measured at birth in 91 preterm infants. In 64% of these babies retinol values were less than 20 micrograms/dl, suggestive of vitamin A deficiency. Forty-seven of these infants were observed with sequential measurements of retinol and retinol binding protein through 21 days of age. In babies with respiratory distress syndrome retinol values were similar to those in babies without respiratory distress syndrome. The retinol binding protein levels were lower on the third day of life in babies with respiratory distress syndrome. Babies who developed bronchopulmonary dysplasia had lower concentrations of retinol at birth (P less than 0.05) and on day 21 (P less than 0.05) than did babies who did not develop bronchopulmonary dysplasia, despite receiving recommended intakes of vitamin A. Many preterm infants are deficient in vitamin A at birth, and failure to correct this deficiency may contribute to the development of chronic lung disease.