Pulmonary interstitial emphysema (PIE) is an acquired condition that can develop in premature infants with severe hyaline membrane disease (HMD) who require assisted ventilation. In this study, the effect of surgery on the ventilatory requirements of nine infants with severe and progressive PIE was established to determined the degree to which surgical intervention was beneficial. The median ventilation index for O2([PaO2/(F2O2 × MAP)]) and median ventilation index for CO2 ([PIP-PEEP] × RR × PCO2) markedly improved following surgery. There was no difference in overall outcome between those infants who had a lobectomy and those who had pleurotomy with diathermy deflation of subpleural cysts (POD). Given that PIE is reversible, POD seems to be preferable to lobectomy because it preserves lung tissue.