After a period of 10 years the authors reexamined the respiratory health status of 381 dust-exposed males. Of the lung function values examined Raw, RV/TLC%, VC, TGV and PaO2 were found to be of significant prognostic importance. Among the radiological changes characteristic of silicosis the most serious B-C category, among the respiratory complaints dyspnoea accompanied by regular cough and expectoration, and among the physical changes extended rhonchi and rales accompanied by an emphysematous thorax are to be considered as most essential with respect to prognosis. Smoking habits significantly affected the total death rate, but did not prove to be significant with regard to respiratory death. In the development of bronchial obstruction recurrent febrile respiratory diseases proved to be more important than smoking habits and mild bronchitic complaints.