Stroke is a preventable tragedy for nearly 750,000 people each year. Primary stroke prevention measures applicable to the general public include a healthy diet containing fruits, vegetables, fish, and low fat; exercise; smoking cessation; limiting alcohol to moderate use; and perhaps avoidance of stress. Screening for hypertension, cholesterol, heart disease, and carotid artery stenosiscan lead to even more effective stroke prevention in high-risk patients. Specific antihypertensive drugs such as angiotensin-converting enzyme inhibitors and angiotensin-converting enzyme receptor blockers may be especially protective against stroke. Secondary stroke prevention in patients who have already had a stroke or transient ischemic attack is even more effective in preventing more serious strokes. Measures include antihypertensive and cholesterol-lowering agents, carotid endarterectomy, anticoagulation for atrial fibrillation and other cardiac sources of embolic stroke, and antiplatelet therapy. Stroke prevention depends on the application of these well-known and widely available treatments to a large number of patients.