Atrial fibrillation (AF) is the most commonly encountered arrhythmia in clinical practice but the mechanisms underlying the initiation and maintenance of AF are yet to be clarified. It is well-known that regular exercise is beneficial to health and reduces the risks of cardiovascular diseases. However, recent studies suggest that long-term endurance exercise, including running [1], swimming, rowing [2] and cycling [3], or vigorous competitive sports may increase the incidence of AF in these athletes. This review article is intended to provide a summary of the possible links between exercise and AF.