Objective: The aim of this study was to investigate the effect of obesity on dispersion of P-wave duration and QTc interval in obese women. Methods: Forty-two obese women (Body mass index (BMI) ¼ 4073 kg/m 2 , mean age 4579 years) and compared agematched (BMI ¼ 2271 kg/m 2 , mean age 4176 years) twenty-five non-obese women were included in our study. Maximum and minimum P-wave duration, P-wave dispersion (difference between the maximum and the minimum P-wave duration), maximum and minimum QTc interval, and QTc dispersion (the difference between the maximum and the minimum QTc interval) were measured from 12-lead ECG. ECG's were transferred to a personal computer via a scanner and then used for magnification of 400 times by Adobe Photoshop software. Results: There was significant difference in BMI (4073 vs 2271 kg/m 2 , Po0.001, respectively) between obese and non-obese women. Obese women had higher Max. P-wave duration (116711 vs 94714 ms, Po0.001), P-wave dispersion (51715 vs 26711 ms, Po0.001), Max. QTc interval (449738 vs 419730 ms, Po0.001) and QTc dispersion (57723 vs 38715 ms, Po0.001) compared to non-obese women. A significant correlation was found between BMI and Max. P-wave duration (r ¼ 0.584, Po0.001), P-wave dispersion (r ¼ 0.621, Po0.001), Max. QTc interval (r ¼ 0.410, Po0.001), and QTc dispersion (r ¼ 0.429, Po0.001). In the linear regression analysis, compared to co-morbidity factors such as age, hypertension, diabetes mellitus and smoking, there was significant association between only BMI and electrocardiographic values (P-wave and QTc dispersion). Conclusion: We concluded that obesity caused significant increase in P-wave and QTc dispersion. Therefore, obese women may not only be under the risk of ventricular arrhythmias, but also they may under the risk of atrial arrhythmias.