OBJECTIVE Ventricular repolarisation changes may lead to sudden cardiac death in obese individuals. We aimed to investigate the relationship between ventricular repolarisation changes, echocardiographic parameters, anthropometric measures, and metabolic syndrome laboratory parameters in obese children. METHODS The study involved 81 obese and 82 normal-weight healthy children with a mean age of 12.3 ± 2.7 years. Anthropometric measurements of participants were evaluated according to nomograms. Obese patients were subdivided into two groups; metabolic syndrome and non-metabolic syndrome obese. Fasting plasma glucose, fasting insulin, and lipid profile were measured. QT/QTc interval, QT/QTc dispersions were measured, and left ventricular systolic and diastolic measurements were performed. RESULTS Body weight, body mass index, relative body mass index, waist/hip circumference ratio, and systolic and diastolic blood pressures were significantly higher in obese children. QT and QTc dispersions were significantly higher in obese children and also obese children with metabolic syndrome had significantly higher QT and QTc dispersions compared to non-metabolic syndrome obese children (p < 0.001) and normal-weight healthy children (p < 0.001). Waist/hip circumference ratio, body mass index, and relative body mass index were the most important determinant of QT and QTc dispersions. Left ventricular wall thickness (left ventricular posterior wall thickness at end-diastole, left ventricular posterior wall thickness at end-systole, interventricular septal thickness at end-diastole) and left ventricular mass index were significantly higher and ejection fraction was lower in obese children. Left ventricular mass index and interventricular septal thickness at end-diastole were positively correlated with QT and QTc dispersions. CONCLUSIONS Our study demonstrated that QT/ QTc interval prolongation and increase in QT and QTc dispersion on electrocardiogram may be found at an early age in obese children.