Background: Atrioventricular nodal reentry tachycardia (AVNRT) is the most common type of supraventricular tachycardia, and catheter Slow pathway ablation is the first-line therapy in this arrhythmia. The endpoint for the successful ablation of AVNRT is the noninducibility of the tachycardia rather than the complete ablation or modification/ablation of Slow pathways. We aimed to compare heart rate variability (HRV) parameters between Slow pathway complete ablation and Slow pathway modification/ablation for AVNRT. Methods: The current study enrolled 78 eligible patients with AVNRT. Slow pathway complete ablation was performed on 49 patients, and 29 patients underwent Slow pathway modification/ablation. HRV parameters on 24-hour Holter monitoring were compared before and 30 days after ablation between these 2 groups. Results: HRV parameters, consisting of the mean heart rate, the standard deviation of normal-tonormal RR intervals over 24 hours (SDNN), the standard deviation of the average NN intervals for all 5-minute intervals in a 24-hour continuous electrocardiographic recording (SDANN), and a percent NN interval exceeding 50 milliseconds from the prior interval (PNN50), were not significantly different in the group with complete Slow pathway ablation. The comparison between pre and post-intervention entities revealed statistically significant differences in SDNN (P=0. 041) and PNN50 (P=0. 008) in the group with Slow pathway modification/ablation. Additionally, PNN50 was significantly lower in the modification/ablation group than in the complete ablation group. Conclusions: We noted negligible differences regarding HRV-associated indices between the Slow pathway complete ablation and modification/ablation for AVNRT groups.