Abstract
Three cases of the neonatal respiratory distress syndrome are described. The babies were treated by prolonged oxygen given by intermittent positive pressure respiration after endotracheal intubation. Two of the infants died and at necropsy the lungs in both cases were consolidated. Both showed widespread haemorrhagic exudate and interstitial oedema. Early organization of the exudate was apparent in one case. The third infant survived but developed a similar exudative condition and a ;honeycomb' lung. It is suggested that many of the changes found in the lungs of these cases could be attributed to the toxicity of oxygen.