Allthough progress is being made in treatment of acute ischemic stroke to reduce the size of the cerebral infarct and thereby lessen the severity of the neurologic deficit, it seems likely that prevention holds the key to reducing death and disability from stroke. Prevention requires the major stroke precursors to be identified, these include risk factors; increasing blood pressure level, diabetes, cigarette smoking, low levels of physical activity, increased fibrinogen level; positive family history of stroke, extremes of alcohol consumption; left ventricular enlargement either left ventricular hypertrophy by ECG (or preferably left ventricular mass by echocardiography), as well as predisposing diseases; coronary heart disease, cardiac failure, and atrial fibrillation. Other cardiac abnormalities, increased left atrial size and mitral annular calcification have also been implicated. High total cholesterol or low HDL-cholesterol has not been consistently related to ischemic stroke, while low levels of total cholesterol have been related to intracerebral hemorrhage. Clinical trials have provided evidence that reducing blood pressure, systolic as well as diastolic, reduces stroke incidence and that warfarin anti-coagulation prevents stroke in atrial fibrillation. Recent trials of rigid control of blood sugar in insulin dependent diabetics suggest that vascular complications may also be prevented by improved management. Observational data strongly support cessation of cigarette smoking and promotion of moderate physical activity as a means of significant stroke reduction. Recent trials of HMG CoA reductase inhibitors for cholesterol reduction have disclosed a striking reduction in cardiovascular events including stroke perhaps via an effect of these drugs on plaque rupture, lesion activation and endothelial dysfunction. Elevated plasma homocysteine levels, amenable to reduction with vitamins particularly folic acid, have also recently been implicated. Identification of persons at increased risk, accounting for the cumulative effect of multiple risk factor abnormalities, is key to stroke prevention. A Framingham stroke risk profile identifies those at high risk and provides each individual's conditional probability of stroke. These high risk individuals can thus be alerted so effective preventive measures may be instituted.