Twenty-one percent of 758 patients (1.1.82-31.8.87) underwent operations for spontaneous pneumothoraces (SPP); 79% were successfully treated with thorax suction drainage. The clinical symptoms and signs did not correlate with BGA values or extent of SPP on x-ray. Thoracoscopy had a diagnostic sensitivity of 70%. Wedge resections (120), partly combined with pleurectomies (63) and pleurodesis (78), were the most frequent operations (death rate 1.6%, recurrence 0.6%). Due to the high rate of recurrence after a first relapse (75%; up to 8 relapses) we recommend surgery at the 1st relapse of SPP, and especially after a relapse. This policy reduces stays in hospital by 37%.