BACKGROUND This study analyzed the long-term effect of leisure-time physical activity on incident cases of coronary heart disease (CHD) among women and men. METHODS A national, random sample of 2,551 women and 2,645 men, aged 35-74, was interviewed in 1988 and 1989 and followed until December 31, 2000, with respect to CHD incident cases. Women and men hospitalized for CHD 2 years before the start of the study and those who rated their general health as poor were not included in the sample. Leisure-time physical activity was divided into four levels according to the frequency of physical activity. The relationship between leisure-time physical activity and CHD was studied in a Cox regression model, adjusted for sex, age, income, smoking, and BMI. RESULTS When leisure-time physical activity increased, the risk of CHD decreased. Women and men who were physically active at least twice a week had a 41% lower risk of developing CHD than those who performed no physical activity (hazard ratio = 0.59, CI = 0.37-0.95), after adjustment for all the explanatory variables. CONCLUSIONS The positive long-term effect of leisure-time physical activity on CHD risk among women and men remains even after accounting for income and other important CHD risk factors.