Spontaneous pneumothorax is an accumulation of air in the pleural space with collapse of the lungs in the absence of external chest trauma. In this clinical study were analyzed of 369 cases of spontaneous pneumothorax experienced at the department of Thoracic and Cardiovascular Surgery, College of Medicine, Chosun University during from January, 1986 to December, 1992.The peak incidence of age was in 3rd decade and more predominantly in male than women [5:1]. Pulmonary tuberculosis was most common etiologic condition and frequently symptoms were dyspnea and chest pain. The site of pneumothorax was Rt.in 48%, Lt.in 45% and both in 7%. The common accompanied diseases were hydrothorax, pyothorax and hemothorax. In 166 cases [45%] were treated by closed thoracostomy only, in 43 cases [12%] were treated by closed thoracostomy & chemical pleurodesis with Tetracycline and in 145 cases [39%] were treated by open thoracotomy. The most serious complication, one case of pulmonary edema, was developed after closed thoracostomy and fatal.