In cases when medicament cardioversion is not successful, the following procedures can be started: cardioversion with electric shock, catheter ablation, electrostimulation or introduction of atrial cardioverter defibrilator. Catheter ablation has been increasingly applied due to new electronic system and more reliable ECG mapping. We treated 16 patients who had atrial fibrillo-flutter (12 men and 4 women), mean age of 62,5 years. Electrodes were placed into the right appendage, coronary sinus and right ventricle via femoral vein and we placed them via femoral artery into the left atrium and ventricle. After electrophysiologic research and ECG endocardial mapping, a successful ablation was achieved in 16 patients. Pacemaker AV modulation was done too. Ablation was unseccessful in 5 patients so 2 were converted into the sinus rhythm by intracardial cardioversion and 3 patients remained on conservative therapy.