The aim of this study was to assess the intensity of physical activity of asthmatic adults in Finland and the associations between the intensity of physical activity and respiratory function in asthmatic and nonasthmatic persons. The study population (n=8000) was drawn from the population register to represent the Finnish population aged 30 years or over. Adequate information was available from 7193 subjects (89.9% of the sample). Physical activity at work, at leisure and during commuting was recorded with a standard questionnaire. The responses to the questionnaire were expressed as MET values. Asthma was defined on the basis of self-reports of chronic diseases previously diagnosed by a physician. The spirometric values (VC, FVC, FEV1, FEV%, and PEF) were negatively correlated with age. The results showed clear and significant associations between spirometric values and intensities of physical activity at work and during leisure time in asthmatic men. Although healthier subjects may select more physically demanding activities, it is an equally possible hypothesis that physical activity may improve respiratory function in subjects with and without bronchial asthma.