Atrial flutter (AF) is a potentially dangerous arrhythmia in children, which is difficult to be converted into sinus rhythm by drug therapy alone. In four young patients (3 had history of cardiac surgery, 1 had Ebstein's anomaly), the AF which had failed to medical therapy was converted into sinus rhythm by an intracardiac atrial pacing: In two patients the AF was terminated by atrial pacing alone, and in the other two the AF was converted into sinus rhythm by atrial pacing after procainamide infusion. In all patients an entrainment of AF was observed during the atrial pacing, which favored a reentrant mechanism for the AF in these patients. Evidences of sinus node dysfunction were observed in all three postoperative patients. We conclude that atrial pacing with or without procainamide infusion is an effective method for the conversion of atrial flutter. In addition, for patients with AF and concomitant sinus node dysfunction, this method can ensure the patients' safetiness.