Acute air leaks such as pneumothorax or pneumomediastinum are a serious and life-threatening complication to infants with the respiratory distress syndrome during mechanical ventilation. Often the clinical diagnosis of an air leak is missed or its seriousness is not fully appreciated. Roentgenograms are the single best diagnostic tool for the early diagnosis of this problem. During 1972 and 1973, a total of 37 infants with respiratory distress syndrome were managed with assisted ventilation; 41% (15) of these infants developed air leaks.