Background and Objective: Childhood obesity is one of the worldwide health problems with an increasing prevalence and accompanied by severe morbidity and mortality. It is a serious predisposing risk factor especially for the development of cardiovascular diseases and arrhythmias. Electromechanical delay (EMD) is known to be a predictor for the development of atrial fibrillation (AF). Our study aims to investigate whether EMD, which is a predictor of AF, prolongs in obese children or not. Material and Methods: The study included 59 obese patients aged between 8-18 years and 38 healthy patients as the control group with a similar age and gender. All the individuals underwent transthoracic echo and tissue Doppler echocardiography. Systolic and diastolic left ventricular (LV) functions, inter- and intra-atrial electromechanical delay were measured by tissue Doppler imaging (TDI) and conventional echocardiography. Results: Obese patients had significantly lengthened P-wave on surface ECG to the beginning of the late diastolic wave (PA) lateral, PA septum, intra- and inter-atrial electromechanical delays when compared with the control group (p < 0.001, p = 0.001, p < 0.001 and p < 0.001, respectively) Inter-atrial EMD and intra-atrial EMD correlated positively with body mass index (BMI) values (r = 0.484, p < 0.001 and r = 0.376, p = 0.001; respectively) BMI was significantly related with inter-atrial EMD (beta = 0.473, p < 0.001) However, there was no relationship between inter-atrial EMD and serum glucose and platelet count. Conclusion: In our study, we declared that electromechanical delay was increased in obese children when compared to the control group and intra- and inter-atrial electromechanical delay was in correlation with body mass index. Furthermore, we discovered that BMI is an independent predictor of the inter-atrial EMD in obese children.