It is well known that idiopathic spontaneous pneumothorax is caused by rupture of the subpleural bleb and presents difficulty in exact detection and localization of the belb with plain chest X-ray alone. The authors performed chest CT scans for accurated diagnosis of bleb that would act as a guide for optimal management of idiopathic spontaneous pneumothrax patients in order to prevent recurrent pneumothorax. We performed chest CT scans from 28 surgically-proven idiopathic spontaneous pneumothorax cases, and 100 blebs were detected from these patients and analyzed. We could detect blebs in 93% (26/28) of the patients with idiopathic spontaneous pneumothorax, and 68%(19/28) of the patient had bilateral blebs. Sensitivity was 0.63, and false negative was 37%(37/100) of the blebs, and 51%(19/37) of these 37 false negative cases were ruptured blebs. Only 7%(2/28) of the patients had a single bleb. The authors concluded that CT is a useful method of study for optimal management of idoiopathic spontaneous.