The occurrence, predictive factors and associated morbidity of bronchopulmonary dysplasia (BPD) was examined in a preterm birth cohort of 712 children, born before 37 weeks of gestation to residents of a geographically defined area between 1978-82. All cases of BPD (N = 16) were born at or before 32 weeks of gestation. The incidence of BPD, based on status at the age of 28 days, was 1 per 1000 live births, but 135 per 1000 live preterms born at or before 32 weeks. Most cases of BPD developed following respiratory distress syndrome (RDS), only one case developing after minimal respiratory symptoms was observed. BPD infants had higher neonatal morbidity, even when compared with preterms of equal gestational maturity, but only a few variables had predictive value with respect to the future development of BPD. Radiologic grading of RDS and associated early cardiologic signs did not increase their predictivity regarding the subsequent development of BPD. Two (12.5%) of the 16 BPD infants died postneonatally. The unfavorable effects of BPD on the health status of preterm infants extended far beyond the neonatal period. The BPD group, which consisted only of 18% of neonatal survivors born at less than or equal to 32 weeks, consumed 53% of all hospital days used by these preterms during the first two years of life. In particular, BPD survivors had markedly more respiratory infections (63%), more neurologic sequelae (37%) and more cases of retrolental fibroplasia (12%) than their non-BPD counterparts.