Three cases with ectopic atrial tachycardia and two cases with atrial flutter (AF), unresponsive to drugs, are described clinically and electrophysiologically. The three patients of ectopic atrial tachycardia were treated by surgical removal of ectopic focus and cryocoagulation of the adjacent area, not using cardiopulmonary bypass. All of them have been in sinus rhythm and had shown no tachycardia since the operation. In one patient of AF, cryosurgical ablation around the atrioventricular (AV) node and His bundle has prevented AF without AV block. Another patient of AF underwent cryoablation around the orifice of the coronary sinus, which was the earliest activation area during AF in endocardial mapping. In this patient, AF reappeared, so cryoablation around the AV node and His bundle was performed. His heart rate decreased to 120 beat/min from 270 beats/min during AF and a radiofrequency pacemaker (Atricon) was implanted to interrupt the remaining AF. This cryosurgical procedure is successful to modify and preserve AV conduction.