BACKGROUND Obesity increases the risk of atrial fibrillation (AF), and AF seriously impairs the quality of life (QoL). However, it is not known whether body mass index (BMI) has any direct influence on QoL in AF. OBJECTIVE To study the association between baseline BMI and QoL improvement in patients with AF following catheter ablation. METHODS Six hundred sixty patients with AF (62 +/- 10 years, male 69%, paroxysmal AF 27%, persistent AF 31%, long-standing persistent AF 42%) made up the study population. On the basis of the baseline BMI, patients were categorized into 2 groups: normal (BMI < 25) and overweight/obese (BMI >= 25). The QoL survey was done at baseline and at 12-month postablation by using the Medical Outcomes Study Short Form-36 (SF-36), Beck Depression Inventory (BDI), Hospital Anxiety and Depression (HAD) scale, and State-Trait Anxiety Inventory (STAI). RESULTS At baseline, dyslipidemia, hypertension, diabetes, coronary artery disease, and large left atrium had higher prevalence in the overweight/obese population. In addition, the preprocedure QoL scores on the SF-36, HAD scale, and STAI were significantly lower in this group than in the normal-BMI group. At the 12-month postablation assessment, no significant improvement in QoL score was noted in the normal-BMI group. However, in the overweight/obese group, QoL scores improved significantly in all scales, except the physical functioning and bodily pain categories of SF-36. Long-term ablation success was not different across the groups (69% normal BMI, 63% high BMI, log-rank P = .109). Patients with successful ablation showed significant improvement in QoL scores compared with those who failed. The multivariable analysis revealed the baseline QoL score and BMI >= 25 to be independent predictors of QoL improvement. CONCLUSION Obese patients with AF tend to have a better postablation QoL outcome than do their nonobese counterparts.