In 1962, a cohort of 4604 Finnish men was interviewed about their smoking habits and cardiorespiratory symptoms. The cohort was followed up for deaths and incidence of lung cancer from 1963 to 1980 in order to study the effect of smoking and cardiac symptoms on the incidence of lung cancer. When analyzed simultaneously with smoking, the symptoms of angina, possible infarction and shortness of breath were all significantly associated with increased lung cancer risk. For example, the RR of lung cancer among those with possible infarction was 2.4, when age and smoking were adjusted for, and 1.8, when additionally shortness of breath and angina-like chest pain were adjusted for. Among smokers of greater than or equal to 15 g/day, those with symptoms of angina displayed a considerable excess risk (RR 2.5). A broad range of impairments of the cardiopulmonary functions seem to be associated with the carcinogenic processes invoked by smoking.