Simultaneous and non simultaneous bilateral spontaneous pneumothorax patients[273] were reviewed retrospectively from April 1986 to March 1990 in the Dept. of Thoracic and Cardiovascular Surgery, Kyung Hee University Medical College. The incidence of bilateral spontaneous pneumothorax was 13.6%[37] and sexual distribution was male dominant [Male:33, Female:4]. The patients were classified into three major groups according to therapeutic methods: Group I [7]; who were treated with simultaneous bilateral operation for unilateral recurred spontaneous pneumothorax through median sternotomy. Mean age was 20.7 years[17 ulcorner28] and follow up duration was 7.7 months [3 weeks ulcorner2 years]. Group II [23];who were treated with staged lateral thoractomy, unilateral thoracotomy and non simultaneous contralateral closed thoracostomy, or simultaneous or non simultaneous bilateral closed thoracostomy. Mean age was 28.6 years [17 ulcorner56] and follow up duration was 9.8 months[one week ulcorner3.5 years]. Group III[10] ;who were treated with simultaneous bilateral operation for simultaneous or non simultaneous bilateral spontaneous pneumothorax through median sternotomy. Mean age was 21.4 years[17 ulcorner28] and follow up duration was 12.8 months[2 weeks ulcorner2.7 years]. Among the patients managed through median sternotomy simultaneously [Group I and III], there were visible blebs or bullous changed lesions mainly in the apicoposterior segment bilaterally in 15 patients[88.2%] Postoperative complications were 3 cases in Group II [wound infection:2 cases, temporary left wrist drop: one case] but none in Group I and III. Spontaneous pneumothorax recurred in 2 cases, one in Group II and another in Group III but none in Group I. 12 cases of 94 patients[12.8%o] who were treated with unilateral thoracotomy needed contralateral thoracotomy mean 14.9 months[7.5 ulcorner 25 months] later. Mean age was 20.9 years [17 ulcorner28]. In conclusion, simultaneous bilateral operation through median sternotomy should be considered in managements of spontaneous pneumothorax, especially in late teens and early twenties except young women for cosmetic reasons.