Background: Cardiac complications, heart failure, and arrhythmias remain as the major causes of death in thalassemia major. Aim: The aim was to detect the early cardiac involvement in patients with β-thalassemia major. Patients and Methods: 56 patients with β-thalassemia major and transfusion burden ≥12 times/year aged 6-16 years were included in our study and classifi ed into 3 groups according to serum ferritin, Group Ι: Consisted of 21 patients with serum ferritin level <2500 ng/mL, Group II: Consisted of 23 patients with serum ferritin level 2500-5000 and fi nally, Group III: Consisted of 12 patients with serum ferritin level >5000 ng/mL. They were subjected to a thorough history taking, routine laboratory investigations and serum ferritin level, electrocardiography, echocardiography, and tissue Doppler imaging (TDI). Results: There was signifi cant increase in septal wall thickness in Group II and Group III compared to Group I, where (P = 0.002, 0.0001), respectively, also, there were signifi cant increase in posterior wall thickness in Group II and Group III compared to Group I, where (P = 0.012, 0.001), respectively. QTc and QT dispersion (QTd) intervals were signifi cantly increased in Group III in comparison to Group I (P = 0.01) while in Group II, QTc and QTd intervals increased in comparison to Group I but were not statistically signifi cant. Left ventricular (LV) diastolic function (E/A ratio) by both standard and tissue Doppler was signifi cantly impaired in Group III and II compared with Group I. Furthermore, left atrial (LA) active emptying fraction was signifi cantly impaired in Group III compared with Group I (P = 0.001) while LV systolic function parameters by TDI were impaired signifi cantly in Group III and II compared to Group I but by standard echocardiography, LV systolic function showed insignifi cant difference between different groups. Conclusion: The increase in LV septal and posterior wall thickness precedes changes in QTc and QTd as a precursor of arrhythmias in β-thalassemia major. Furthermore, LV diastolic function by both methods, impaired LA active emptying fraction and impaired LV systolic function parameters by TDI precedes changes in LV systolic function by standard echocardiography.