In terms of percentage of total deaths, stroke is second and fourth for women and men, respectively, but in terms of potential years of life lost, it is seventh and sixth, respectively. In both women and men, stroke rates have declined. Acetylsalicylic acid has been shown to reduce significantly stroke, death and stroke-related death in men, with no detectable benefit for women. A major hormonal effect appears unlikely to explain the lack of female responsiveness. The risk factors associated with stroke are generally not different in the two sexes. There is evidence that high dose estrogen, hypertension and smoking are important cumulative factors for premenopausal women. The risk of vascular disease is reduced by post menopausal hormone replacement. Pregnancy increases the risk of thrombotic cerebrovascular events, particularly during the second and third trimesters of pregnancy. Heavy drinkers have a fourfold increase and light drinkers a decrease to one-half of relative risk of stroke compared to nondrinkers. Cigarette smoking increases the risk of stroke. Lifestyle may also play a role.