Localisation in one lung only or in one lobe only of lesions of interstitial emphysema is surprising in a diffuse disease such as hyaline membrane disease in premature infants. In the four patients in which this unusual course was seen, cure was obtained in different ways: spontaneously in one case, by excision of a diseased lobe in two cases and by selective temporary intubation of the contralateral main bronchus in the final case. Current methods of treatment of neonatal respiratory distress favour this type of course, without any precise cause being evident. Excision surgery is often avoidable by transient ventilation of the contralateral lung only by selective intubation of the main bronchus.