Summary. Cardioversion to sinus rhythm should be considered for all suitable patients in atrial fibrillation In the short term both pharmacological and electrical cardioversion restore sinus rhythm Prophylactic treatment with antiarrhythmic drugs is advisable after cardioversion in high risk patients in view of the high relapse rate Anticoagulants should be started before non-emergency cardioversion—ideally two to three weeks before—and continued for at least four weeks after cardioversion in patients with atrial fibrillation of >48 hours' duration