A Chest Unit's experience of spontaneous pneumothorax over a 14-year period has been analysed: 236 patients, the majority of whom were young males and were smokers, had a total of 315 episodes of spontaneous pneumothorax during this time. Ninety-five per cent were successfully treated at first attendance by observation alone or by intercostal tube drainage. The choice of treatment did not influence the recurrence rate. The remaining 5% were treated surgically. Altogether 37 pleural abrasions or pleurectomies were performed, half because the lung failed to expand with intercostal tube drainage and the remainder because of one or more further episodes. There were no recurrences following this procedure. When definitive surgery was not performed after a recurrence there was a 40% incidence of third episodes. There was no mortality. The results of this study confirm that the vast majority of cases can be treated successfully under medical supervision with a recurrence rate around 20%. Surgical intervention should be considered in those who have a second episode or when pneumothorax occurs on the other side.