We hypothesized that significant sleep desaturation might occur in infants with bronchopulmonary dysplasia whose awake saturations were between 90 and 92%. Supplemental oxygen was continued until the awake saturation on room air was 90% or greater. Sleep saturations were monitored by oximetry sampling for a 3-min period every hour overnight. Significant desaturation was considered to be present if the saturation fell repeatedly below 88%. There were 39 studies performed in room air, and 14 studies in supplemental oxygen. We demonstrated that patients with acceptable awake saturation may desaturate while sleeping. However, only 1 of 25 patients whose saturation in room air was 92% or more repeatedly desaturated during sleep.