By the early half of the 20th century, the most common cause of spontaneous pneumothorax was considered to be tuberculosis. But recently ruptures of the subpleural emphysema and/or blebs are considered as the major causes of spontaneous pneumothorax. To evaluate the causes of spontaneous pneumothorax, the authors reviewed the 96 patients who were consecutively diagnosed and treated by thoracotomy for spontaneous pneumothorax at the Department of Thoracic and Cardiovascular Surgery, Seoul Advenist Hospital, from May, 1988 to April, 1993. The patients who had clinical and radiological evidence of tuberculosis or other specific parenchymal lung diseases were excluded from this review. All patients were negative for tuberculous bacilli on sputum studies. The pathologic results were as follows : subpleural emphysema[25], blebs[27], subpleural emphysema and blebs[25], pleural fibrosis[10], tuberculosis[8], and parasitic granuloma[1]. Three of the patients who were diagnosed to be tuberculosis by pathologic findings were progressed to active pulmonary tuberculosis on the follow-up chest PA films. The authors conclude that all patients with spontaneous pneumothorax must be evaluated periodically for tuberculosis and that patients who were diagnosed to be tuberculosis by postoprative pathologic report need the administration of the prophylactic antituberculous drug, because the prevalence of tuberculosis remains relatively high rate in our country.