The cardioversion of chronic atrial fibrillation to sinus rhythm carries a thromboembolic risk of 1.5-6%. These events occasionally occur at the time of cardioversion, but more often happen hours or days later. These strokes and other embolic events may occur even where atrial thrombus has been excluded before cardioversion and it has become apparent that, although atrial electrical activity may be restored by cardioversion, normal mechanical atrial function may take longer to recover. Numerous studies have addressed the role of anticoagulation following cardioversion in patients with atrial fibrillation, however, the mechanism of embolic complications as well as the justification of a standard anticoagulation therapy are not fully established. In this review we will try to present an overview of the mechanisms of thrombosis following cardioversion and give an insight into current anticoagulation strategies.