This review of the epidemiological evidence regarding physical activity and cardiovascular disease (CVD) provides substantial evidence from many different populations that leisure time physical activity is associated with reduced risk of coronary heart disease (CHD) and cardiovascular mortality in both men and women and in middle-aged and older individuals. Physical activity appears to be a critical factor in both primary and secondary prevention of CHD. The studies indicate a dose-response relationship between overall physical activity and CVD, which is linear at least up to a certain level of activity. Prospective studies suggest that physical activity is also associated with reduced risk of stroke. The mechanisms underlying the protective effect of physical activity on CVD are still unclear. In recent years. the view that physical activity has to be vigorous to achieve a reduction in risk of CHD has been questioned. Overall, the evidence points to the benefit of continued regular moderate physical activity which does not need to be strenuous or prolonged and includes daily leisure activities such as walking or gardening which are readily attainable by large sections of the population. Taking up regular light or moderate physical activity in middle or older age confers significant benefit for CVD and all-cause mortality.