To study the effect of oxygen therapy on weight gain in bronchopulmonary dysplasia (BPD), the growth of 22 infants with BPD enrolled in a premature follow-up clinic and home oxygen program was examined retrospectively. Mean gestational age was 28 weeks (range, 26 to 33 weeks) and mean birth weight was 1110 g (range, 680 to 2000 g). After discharge, infants were monitored monthly to maintain transcutaneous oxygen tension over 55 mm Hg and/or pulse oximeter oxygen saturation over 92%. With appropriate home oxygen, all 22 infants grew as well as healthy, full-term infants (mean, 40th percentile; range, tenth to 80th percentile) when ages were corrected for prematurity. Parents discontinued oxygen therapy inappropriately in seven infants, and all seven experienced significant deceleration in weight gain. When home oxygen therapy was resumed, their weight gain improved, but the infants never regained their original percentiles during the study period. The 15 infants who continued home oxygen therapy maintained their original weight percentiles throughout the study period. These data support an important role for home nasal cannula oxygen in promoting weight gain in selected infants with BPD.