The risk of cerebral infarction in patients with atrial fibrillation varies from 0.5% to more than 10% per year. Anticoagulant therapy is recommended today more than before, but to a low-risk patient anticoagulation may cause harm that is larger than the expected benefit. Assessment of the risk of cerebral infarction is therefore essential. Use of the CHA2DS2-VASc risk index enables reliable identification of low-risk patients who do not benefit from anticoagulation. Individual treatment decisions may even be necessary.