The initial treatment of 135 patients who had spontaneous pneumothorax consisted of controlled thoracotomy tube suction. Prompt expansion of the lung without subsequent collapse was obtained in 81% of the patients so treated. The average period of hospitalization was 5 days. Thoracotomy, with resection of emphysematous blebs and abrasion of the parietal pleura were necessary in 30 patients because of recurrence, tube failure, or presence of large blebs. Bilateral resection of blebs was performed in 1 patient with simultaneous bilateral pneumothorax. Clinical investigation at the time of the occurrence of the spontaneous pneumothorax, microscopic examination of the tissue removed at surgery, and follow-up studies up to 10 years failed to demonstrate tuberculosis in any of these persons. Emphysematous blebs were found in all patients who underwent thoracotomy.