Background: Recent studies have demonstrated the association of 4q25 gene single nucleotide polymorphism (SNP) with atrial fibrillation (AF). We evaluated potential relationships of 4 SNPs on chromosome 4q25 with clinical and electrophysiological characteristics in patients undergoing catheter ablation for AF. Methods: A total of 295 consecutive patients (mean age 56짹11 years, 78% male) with drug-refractory paroxysmal (68.7%) or persistent (31.3%) AF who underwent AF catheter ablation were included. Genotyping for 4 SNPs in close proximity to PITX2 gene on chromosome 4q25 (rs2200733, rs10033464, rs17042171, and rs6843082) were performed and compared with clinical, electrophysiological, and imaging database. Results: There were no significant differences in clinical and electrophysiological parameters between major and minor allele group of rs10033464, rs17042171, and rs6843082 (all p value>0.05). In contrast, rs2200733 variant was associated with lower CHADS score (0.73짹0.95 vs. 1.17짹1.10, p=0.021), lower prevalence of heart failure (2.5 vs. 11.5%, p=0.023), hypertension (42.3 vs. 68.9%, p=0.006), and patients with age >75 (1.2 vs 6.9%, p=0.030). In electrophysiological study, conduction velocity of posterior wall was significantly higher (0.67짹0.35 m/s vs. 0.55짹0.22 m/s, p=0.042) in patients with variant allele of rs2200733. Conclusions: In Korean population, rs2200733 at 4q25 was the only significant SNPs associated with clinical and electrophysiological trait. It may increase the risk of AF without traditional co-morbid risk factors and significant electroanatomical remodeling.