Abstract: AIM: To investigate the cause of atrioventricular nodal reentrant tachycardia (AVNRT) recurrence after slow pathway radiofrequency catheter ablation (RFCA). METHODS: Three hundreds and fifty-six cases with AVNRT after RFCA were followed up and their electrophysiologic data were retrospectively analyzed. RESULTS: Ten of the 356 cases had recurrence (2.8%). No recurrence was observed in the 320 cases without an atrial echo and jump phenomenon after RFCA. Three cases recurred from the 17 cases with an atrial echo but no jump phenomenon in those where no supraventricular tachycardia (SVT) was induced after RFCA. Five cases recurred in the 11 cases with an atrial echo and jump phenomenon but no SVT after RFCA. Two cases recurred from the eight cases with jump phenomenon but no atrial echo and no SVT after RFCA. Among the 10 recurrent cases, atrioventricular nodal refractory period (AVNERP) after the second RFCA obviously lengthened compared with that after the first RFCA and the difference between AVNERP and fast pathway ERP obviously diminished. No recurrence was observed in the 10 recurrent cases who had been treated with a second RFCA (>9 months). CONCLUSION: Slow pathway remnant is the main cause of AVNRT recurrence after slow pathway RFCA.