Exercise is associated with positive health habits: Findings from the populations survey of the Swiss MONICA-project. Relatively little is known on population-wide relations of habitual exercise to relevant health factors such as diet, cigarette smoking and overweight. Data from a population-based sample of approximately 800 men and women each, aged 25-64, collected in western Switzerland as a part of an international WHO-project, were used to examine cross-sectionally the interrelationships between different lifestyle factors. Men and women training regularly (i.e. greater than or equal to 2 times/wk) exhibited consistently and highly significantly more favourable health habits, regarding diet (i.e. trimming visible fat, higher intake of fruits, salad and vegetables, yogurt and cottage cheese), nonsmoking, and weight control. Men and women with at least some regular physical activity during leisure-time had in turn more favourable health habits than their sedentary counterparts. In both sexes, educational level was directly related to exercise and a healthy diet, and inversely related to smoking and relative weight. Regularly training men and women also had a significantly improved lipid profile compared to inactive ones. It is concluded from this study that leisure-time physical activity and exercise are related to a positive health behaviour including diet, nonsmoking and efficient weight control. This may suggest that exercise should possibly be integrated into any population-wide attempts and efforts to promote health to enhance primary prevention.