Experience with 300 episodes of spontaneous pneumothorax in 209 patients is reported. The treatment results of two time periods 1980-1983 (A) and 1985-1987 (B) are compared. During the second period the diagnostic work-up was much more extensive and included pleurography, CT-scan and thoracoscopy. This resulted in a more differentiated therapy and a reduction in the recurrence rate from 41% to 22%. Among the different modes of treatment chest-tube drainage alone had the worst results with a 44% rate of early and late recurrence. Better results were obtained with pleurodesis using fibrin adhesive either through a pleural catheter (24%) or thoracoscopically (13%). Operative treatment had the lowest recurrence rate (4%). In the primary treatment of spontaneous pneumothorax chest-tube drainage had a recurrence rate of 33% and catheter-pleurodesis with fibrin adhesive of 18% while no relapse could be observed in the group treated by thoracoscopy or operation. In the treatment of recurrent pneumothorax chest-tube drainage alone is unsuitable because of a failure rate of 64%. Catheter pleurodesis also had a high rate of recurrence (30%). The best results were again obtained by thoracoscopic (19%) and operative treatment (4%). On the basis of the described experience an individualized approach to the treatment of spontaneous pneumothorax is recommended.