In a prospectively randomized study we investigated the influence of vitamin E on the development of bronchopulmonary dysplasia (BPD) in neonates with artificial ventilation. Out of 78 neonates two randomized groups of each 39 were formed; one was treated, the other served as control group. We evaluated the cases of those children who remained on respiratory therapy for more than 3 days and who survived 14 days or longer, 19 in each group. The vitamin E treated infants received 20 mg/kg vitamin E i.m. daily during artificial ventilation, but not longer than 14 days. A total of 5 infants (13%) developed BPD, 3 in the vitamin E group, 2 in the control group. All patients with BPD died after 1/2-4 months. After 3 months 17 treated and 16 untreated infants survived. X-rays of the lungs were normal in 12 and 13 respectively. These results do not suggest a beneficial effect of vitamin E in respirator-treated newborn infants.