Electrical cardioversions are performed to restore sinus rhythm in patients with non-valvular atrial fibrillation to improve symptoms. It has been known for decades that cardioversion without adequate anticoagulation for 3-4 weeks prior to and for 4 weeks after cardioversion results in thromboembolic complication of about 5%. It is much less known that cardioversion is also associated with a higher risk of thromboembolism (stroke, peripheral embolism) in patients treated with usual anticoagulation. The control arms (warfarin) of the three studies with the new anticoagulants dabigatran, rivaroxaban, and apixaban for the prevention of thromboembolism in non-valvular atrial fibrillation report a monthly thromboembolic risk of 0,13-0,2%. The risk for thromboembolic complication in the month following cardioversion is about three to six times higher than without cardioversion in patients with non-valvular atrial fibrillation treated with usual anticoagulation. Since most cardioversions are performed by DC shock it is not known whether electrical and pharmacological cardioversions carry the same risk for thromboembolism. Although thromboembolic complications do not often occur following cardioversion the increased risk due to this procedure should be acknowledged. Strict anticoagulation (e. g. INR value > 2,5) in the first 10-14 days following cardioversion could possibly minimize the risk of thromboembolism.