To discover the prevalence of chronic respiratory disease and the various factors associated with it, 1162 men (85% of the defined population) aged 25 to 69 years were surveyed using a questionnaire, chest radiograph and spirometry. 112 men with pulmonary tuberculosis or "other respiratory disease" were excluded from the analysis. Excluding the youngest age group (25 to 39 years), the smokers were thinner than the non-smokers. The percentages of overweight men among the non-smokers, ex-smokers and smokers were 22%, 27% and 14%, respectively (P less than 0.001). Almost all respiratory symptoms were more common in the smokers than in the non-smokers, and the prevalence of cough, phlegm, severe breathlessness and the effect of weather on respiratory symptoms significantly increased with age. Asthma was not associated with age or smoking, nor was socioeconomic status associated with chronic respiratory disease. The ventilatory function, measured by FEV1, FVC and FEV%, was worse in the smokers than in the non-smokers. In addition the slope of FEV% on age was significantly steeper in the ex-smokers and the various groups of smokers than in the non-smokers.