Atrial fibrillation has the highest prevalence in the elderly. While the elderly are at the highest risk for stroke and would benefit the most from anticoagulation, they are also the least likely to receive anticoagulation. In a pooled analysis of the primary prevention trials, warfarin reduced stroke by 68% compared with placebo, and aspirin reduced stroke by 18%. Age, history of hypertension, diabetes, heart failure or reduced left ventricular function, and previous transient ischemic events and stroke are independent risk factors for stroke in patients with atrial fibrillation. Less than 50% of the elderly who have clear-cut indications and no contraindications for warfarin receive anticoagulant therapy. This low use of warfarin is driven by many factors, but physicians' fear of hemorrhage is among the most important. Better adherence to evidence-driven guidelines, better patient and physician education, point-of-care monitoring of INR and the future development of user friendly anticoagulant drugs are likely to result in higher rates of anticoagulation use.