Disorders of cardiac rhythm, which most commonly occur in our patients operated using beating heart procedure, are supraventricular tachycardia, artrial fibrillation, atrial flutter and ventricular extra beats. The most frequent causes of arrhythmias were myocardial ischemia, electrolyte imbalance, hypothermia and impairment of acid -base status. We commonly employ aggressive treatment for all arrhythmias with standard medication and electroconversion, particularly if early hemodynamic sequels occur. Our experience shows less arrhythmias associated with beating heart procedure compared to surgery with cardiopulmonary bypass so we perform this procedure whenever possible.