To test the hypothesis that the short-term (approximately 6 months) course of babies with bronchopulmonary dysplasia (BPD) could be predicted from the clinical and radiological status on day 28 of life, we retrospectively examined the medical records of 79 infants born between 1985 and 1988 who required supplemental oxygen and/or ventilatory support on day 28. Chest roentgenographs taken close to day 28 (+/- 7 days) were scored on a scale of 0-10. Four babies died from causes not related to BPD. Four of the remaining 75 died from BPD, and the rest are alive. Forty-six of 71 were weaned from supplementary oxygen by 37 weeks corrected gestational age, and only 13/71 remained on supplemental oxygen after 40 weeks gestational age. To determine which variables contributed most to the outcome, defined as total days on supplemental oxygen, a multiple regression analysis was performed, including only those variables the tolerance of which exceeded 0.7 (sex, FiO2, ventilatory mode, and infectious status). FiO2 and ventilatory mode together predicted 15% of the variability in outcome, so that a high FiO2 and ventilator dependence on day 28 of life were highly correlated with a prolonged need for supplemental oxygen (F = 4.28, P < 0.05).