Between 1984 and 1994, 27 men and 4 women with primary spontaneous pneumothorax were treated surgically by excision of the bullae, without pleurectomy. The purpose of the present study was to establish by computed tomography (CT) of the lung whether the excision permanently eliminated the cause of pneumothorax. The median follow-up was 72 (21-127) months. There were two patients with recurrences (6.4%) who were operated on again. Sixteen of 31 patients had new blebs in the apex of the lung as documented by postoperative CT. The study indicates that simple excision of the bullous area cannot prevent the recurrence of blebs.