After talc pleurodesis performed between 1954 and 1964 because of spontaneous pneumothorax during thoracoscopy, 99 patients were followed up. Only 2 patients experienced a pneumothorax relapse. Mesothelioma was not observed in any case, X-ray changes in the Pleura were moderate, and lung function did not show any significant restriction. It is concluded therefrom that the method is effective and does also not produce any noticeable side effects on long-term observation.