Introduction: Catheter ablation is a cornerstone of the therapy for the paroxysmal atrial fibrillation. The importance of effective lesion size formation during pulmonary vein isolation is gauged through conduction recovery and recurrence of arrhythmia. Therefore, lesion size index (LSI) It is designed to utilize traditional intraprocedural parameters and predict the procedural success. The impact of the optimal LSI index and the respective segments of the pulmonary veins has not been commonly evaluated. We aimed to assess whether higher and targeted LSI on the different segments of pulmonary veins could actually leads to better clinical outcomes of paroxysmal atrial fibrillation ablation. Methods: Retrospective analyses of drug-refractory paroxysmal atrial fibrillation patients who underwent first catheter ablation were conducted. Targeted LSI of 6.5 at the anterior wall and 5.2 at the posterior wall, roof and floor of pulmonary vein was applied. The primary endpoint was defined as arrhythmias recurrence assessed by routine electrocardiograms and 24 hours ambulatory electrocardiographic monitoring at 3, 6, and 12 months postablation. Results: Among the included 39 patients, the single-procedure 12-months freedom from arrhythmias was reached in 92.3% patients. Interestingly, there was no tendency towards a increased number of adverse effects using higher LSI index. Conclusion: Atrial fibrillation ablation guided by targeted LSI value showed efficiency on the freedom from arrhythmias during 1-year follow up period without harmful effects.