Premature infants (56) with a mean gestational age at birth of 30 wk were randomly assigned to a transfusion group, for whom the Hb level was kept above 10.0 g/dl, and a nontransfusion group, who were transfused only for specific clinical indications. The groups were followed up longitudinally with weekly determinations of reticulocyte count, the partial pressure of O2 at which 50% of Hb is saturated, and Hb F percentage, as well as weight gain, length of stay, hospital cost and frequency and severity of apnea. At birth, there was no significant difference in birth weight, gestational age, and Hb level between the 2 groups. At discharge, laboratory differences were noted between the 2 groups, but there was no clinical difference. No clinical advantage was found to the use of booster RBC transfusions in growing premature infants.