The term accelerated idioventricular rhythm describes an ectopic ventricular rhythm with 3 or more consecutive ventricular premature beats with a rate faster than the normal ventricular intrinsic escape rate of 30 to 40 beats per minute, but slower than ventricular tachycardia. Accelerated idioventricular rhythm differs from ventricular tachycardia by additional features such as the onset with a long coupling interval, the end by a gradual decrease of the ventricular rate or increase of the sinus rate and, last but not least, by a good prognosis. Clinically, accelerated idioventricular rhythm can occur in any form of structural heart disease and occasionally in adults or children without structural heart disease. Accelerated idioventricular rhythm most often can be seen in patients with coronary artery disease. Its occurrence after thrombolysis during acute myocardial infarction is a marker of successful reperfusion. Since accelerated idioventricular rhythm is usually hemodynamically well tolerated and not associated with malignant ventricular tachycardias; as a rule, no specific treatment other than care of the underlying heart disease is necessary. The present overview discusses electrocardiographic criteria, possible mechanisms, and the clinical significance of accelerated idioventricular rhythms.