Postmortem chest roentgenograms in approximately 3,500 cases of a random autopsy population were reviewed. Pneumothorax was found in 77 cases (2.2%). Simple pneumothorax was present in 38 cases, and tension pneumothorax or combined simple and tension pneumothorax was present in 39 cases. Only 40 of the 77 patients had been clinically diagnosed as having pneumothorax. Pulmonary conditions most often present in cadavers with pneumothorax were bacterial pneumonia, pulmonary emphysema, and pulmonary embolism, with or without infarcts and infarct abscesses. Procedures most frequently associated with pneumothorax were mechanical ventilation and attempts at cardiorespiratory resuscitation. Rib fractures (iatrogenic and noniatrogenic) were found in 23 of the 77 cases.