We conducted a retrospective study of patients treated in our department for primary spontaneous pneumothorax (PSP) between 1986 and 1993. The 495 patients were between 12 and 81 years old (mean 28.2 years). Four hundred fifteen (83.8%) were men and 80 (16.2%) were women. PSP was in the right lung in 262 cases (52.9%) and in the left lung in 215 (43.5%). Both sides were affected in 18 cases (3.6%). The initial treatment was pleural drainage; small caliber drains were used in 85 and no associated complications were observed. On 185 occasions (37.3%), patients required surgical repair as a result of air leaks, recurrence or acute hemorrhage. There were postsurgical complications in 15 cases (8.1%) but no recurrences or deaths after surgery. We observed no significant differences in the number of recurrences after use of conventional drains or small caliber drains. Nor were there differences in mean time of hospital stay or complications after conventional surgery or video assisted surgery, a technique that has only recently been introduced. We conclude that PSP responds well to treatment with pleural drains and that small caliber catheters offer a good alternative for treating first episodes. Surgery is indicated when there is recurrence or when air leaks are persistent. At present, video assisted thoracoscopic surgery has successfully replaced axillary thoracotomy for most patients.