Several meta-analyses support the importance of participation in regular, leisure-time physical activity for the primary prevention of stroke and cardiovascular disease, as well as other associated health benefits. Whether both men and women benefit is not clear, in part owing to there being relatively fewer women in relevant observational and case-control studies. Data from the Women's Health Study have now been used to address this question in a large cohort of women. After multivariable adjustment, increasing levels of leisure-time physical activity in women tended to be associated with lower stroke risk, with a particular benefit of regular, brisk walking for those who did not vigorously exercise. The results reinforce recommendations that both men and women participate in regular, leisure-time physical activity.