Iron overload is associated with an increased risk of atrial and ventricular arrhythmias. Data regarding the relationship between electrocardiographic parameters of atrial depolarisation and ventricular repolarisation with cardiac T2* MRI are scarce. Therefore, we aimed to investigate these electrocardiographic parameters and their relationship with cardiac T2* value in patients with beta-thalassemia major. In this prospective study, 52 patients with beta-thalassemia major and 52 age- and gender-matched healthy patients were included. Electrocardiographic measurements of QT, T peak to end interval, and P wave intervals were performed by one cardiologist who was blind to patients' data. All patients underwent MRI for cardiac T2* evaluation. Cardiac T2* scores less than 20 ms were considered as iron overload. P wave dispersion, QTc interval, and the dispersions of QT and QTc were significantly prolonged in beta-thalassemia major patients compared to controls. Interestingly, we found prolonged P waves, QT and T peak to end dispersions, T peak to end intervals, and increased T peak to end/QT ratios in patients with T2* greater than 20 ms. No significant correlation was observed between electrocardiographic parameters and cardiac T2* values and plasma ferritin levels. In conclusion, our study demonstrated that atrial depolarisation and ventricular repolarisation parameters are affected in beta-thalassemia major patients and that these parameters are not correlated with cardiac iron load.