Accelerated idioventricular rhythm(AIVR) describes ventricular rates slower than usual tachycardia rates but faster than the ventricular escape rhythm. Ventricular rates of 40- 120 beats/min are usual. Accelerated idioventricular rhythm probably represents enhanced automaticity in the ventricles and manifests itself when sinus rates slow. This arrhythmia has been reported in association with acute myocardial infarction, digitalis excess, cardiomyopathy, and rheumatic heart disease. Only rare case of AIVR without underlying heart disease has been described. It is transient and intermittent, with episodes lasting a few seconds to a minute, and does not appear to seriously affect the patient's clinical course or the prognosis. Suppressive therapy is rarely necessary. Recently, we have experienced four cases of AIVR in children without underlying heart disease with benign clinical course.