The aim of this article is to demonstrate the impact of physical exercise on the development of arrhytmias in athletes. The studies show that this relation exist and concerns endurance sports practiced for a long time. In addition, this article contains review of the most common arrhythmias in athletes and appropriate recommendations. The time of arrhythmias onset depends on the presence of structural heart diseases. If the cardiac disorder is absent the arrhythmias appear at the age 40-50. If the structural heart diseases exist, the arrhythmias occur in young athletes and are more dangerous (can lead to sudden cardiac arrest). The most common arrhythmia in endurance athletes is atrial fibrillation. In order to avoid negative results of endurance sports, such as cardiac arrhythmias, the reliable examinations are necessary, especially to exclude structural cardiac diseases. These examinations should be undertaken before initiation of endurance sport training and routinely later, in course of follow-up.