A 30-year-old man with a structurally normal heart was referred to us with a 2-year history of recurrent episodes of rapid paroxysmal palpitations. A few episodes required hospitalization and were terminated with intravenous diltiazem. During electrophysiology (EP) study done twice before in other hospitals, the patient was diagnosed as typical atrioventricular nodal reentrant tachycardia (AVNRT) and underwent radiofrequency ablation of the slow pathway. However, the episodes recurred.  Because of the patient’s persistent symptoms, an EP study was performed again. Tachycardia was easily induced using atrial extrastimuli, ventricular extrastimuli and with rapid atrial pacing.