The reported incidence of Bronchopulmonary dysplasia (BPD) varies from 5% to 68%. The different criteria used to define BPD are responsable for these discrepancies: some Authors include only patients with a clinical and radiological picture that fits the stage IV, as originally described by Northway, others use a more liberal approach and include all patients with manifestations of chronic pulmonary disease. We observed BPD in 12 of 22 (54%) survivors infants of very low birth weight (mean 1115 gm) and gestational age (mean 29,2 weeks). The infants were all born between November 1979 and March 1981. According to Ehrenkranz et al., we classified the radiological findings as severe, moderate and mild. We believe that the etiology of BPD in very low birth weight infants is multifactorial. However, pulmonary oxygen toxicity and immaturity are the most important causes.