Atrial flutter (TP) is one of the most common supraventricular tachyarrhythmias. Because of its influence on hemodynamics of the circulation, prolonged episode of paroxysmal TP can lead in as many as 1/3-1/2 patients to clinical signs of coronary insufficiency, decompensation of the circulatory system, or even such life-threatening states, like cardiac arrest. Patients with preexcitation syndrome, hyperthyroidism, as well as children, whose atrio-ventricular (AV) node can conduct in a 1:1 fashion, are in the group of particularly high risk of complications. Recurrent episodes of TP are also associated with frequent occurrence of thromboembolic events. Based on the electrocardiographic (ECG) pattern TP is divided into common type, with negative "sawtooth" in leads II, III, aVF, and uncommon type, which is characterised by other ECG morphologies. Experimental and clinical data have revealed, that common and some part of uncommon type are due to clockwise or counterclockwise reentry in the right atrium. These forms of TP can be treated with high success-rate with radiofrequency (CR) ablation. Because of difficulties in pharmacological conversion of the arrhythmia to the sinus rhythm and high frequency of recurrences, CR ablation seems to be a high effective method of treatment in patients with common and some forms of uncommon TP.