The objective of this follow-up study was to evaluate the success rate of different therapy procedures in spontaneous pneumothorax. In order to achieve comparable conditions the study was restricted to those patients who were treated because of a first episode (n = 96) in the time between January 1978 and December 1987. Seventy-one were males and 25 females, ratio 3:1. The right side to left side ratio was 3:2. Both sides were affected in 11% (n = 11). All patients received an intercostal tube drainage with a permanent suction. In case of treatment failure thoracoscopy, pleurodesis or an operation were performed. The follow-up investigations was performed in January 1990 thus to further evaluate the outcome of 79 patients (82%) after 2 to 12 years after treatment. Among the patients, 33 patients presented a persistence or an early recurrence, 26 of them were operated during their first stay in hospital. A further 25 patients presented a late recurrence, of whom 14 underwent a later thoracotomy. Consequently the drainage therapy had a failure rate of 61% (n = 58). The frequency of operation was 42% (n = 40). The results after thoracotomy (n = 26) were as follows: slight complications, which did not require surgical treatment occurred in 8% (n = 2). The long-term results after surgical intervention (lung apex resection and/or parietal pleurectomy) were excellent concerning the rate of late recurrences (0% within the follow-up group) and the general condition (96% free or almost free of symptoms) regardless the method of operation.(ABSTRACT TRUNCATED AT 250 WORDS)