Infants with bronchopulmonary dysplasia (BPD) experience significant hypoxemia. Apnea indices and oxygen saturation levels of ten infants with BPD were compared to ten healthy premature infants who were evaluated to rule out apnea or bradycardia prior to discharge from the hospital. Infants with BPD who had been recently (less than 7 days) weaned from supplemental oxygen were evaluated on and off supplemental oxygen. Premature controls had never received oxygen nor ventilation assistance. Infants with BPD were born significantly more prematurely (28.1 +/- 1.0 vs. 33.0 +/- 3.9 weeks; P = 0.0012) while chronologic ages at the time of evaluation, adjusted for prematurity, were equal (37.1 +/- 3.1 vs. 38.0 +/- 2.7 weeks). Comparisons of apnea densities (expressed as percent of sleep time) between BPD and non-BPD prematures revealed the following: neither the average obstructive apnea (0.15 +/- 0.36 vs. 0.14 +/- 0.31) nor periodic breathing densities (6.0 +/- 8.56 vs. 10.2 +/- 5.84) were different. Infants with BPD experienced significantly more central apnea (0.62 +/- 0.34 vs. 0.16 +/- 0.11; P = 0.003) than did non-BPD prematures. Average oxygen saturation levels were significantly less among BPD vs. non-BPD prematures (90.0 +/- 10.18% vs. 95.7 +/- 4.33%; P = 0.033). When supplemented with oxygen, BPD prematures had significantly higher saturation (X = 94.5%) than when breathing room air (X = 90.0%). Both central apnea and periodic breathing densities declined significantly with this improvement in saturation (0.64 vs. 0.04% and 6.0 vs. 1.4%, respectively). These data suggest that saturation status may indicate central respiratory stability in chronic lung disease.