We have reviewed 330 cases of spontaneous pneumothorax from Jan. 1980 to Jul. 1987 at the department of Thoracic and Cardiovascular Surgery, College of Medicine, Korea University. The ratio of male to female was 8.4:1, predominant in male. The incidence according to the age group was highest as 32% in the adolescence between 21 and 30 years old. The site of pneumothorax was right in 48%, left in 45% and bilateral in 7%. The initial symptoms were frequently dyspnea in 85%, chest pain in 63%. The etiologic factors were as follows; bleb origin in 31%, tuberculous origin in 30%, COPD in 3.3%, lung cancer in 1.5%, unknown in 29%. There was no significant difference in seasonal incidence irrespective of tuberculous or sex. The employed managements were as follows; bed rest with oxygen inhalation in 4 cases, closed thoracostomy in 326 cases, open thoracotomy in 122 cases, median sternotomy in 23 cases. The operative procedures at thoracotomy were as follows; simple pleurodesis in 5 cases, bleb excision or wedge resection in 113 cases, segmentectomy or lobectomy in 17 cases, decortication in 42 cases. Recurrence rate of each treatment was as follow; 50% in conservative treatment, 19% in closed thoracostomy, 2% in open thoracotomy, 4% in median sternotomy. Therefore overall recurrence rate was 12%. Open thoracotomy was the most effective procedure in recurrent pneumothorax, previous contralateral pneumothorax, bilateral simultaneous pneumothorax, visible bleb or bullae on the chest x-ray and persistent air leakage. 23 cases of unilateral spontaneous pneumothorax was examined whether or not underlying pathology of pneumothorax at opposite lung. 18 cases[78%] were positive findings. Therefore, bilateral thoracotomy by median sternotomy was a good operative method preventing contralateral pneumothorax.