Aim: This study aimed to evaluate the role of real-time three-dimensional (four-dimensional) and speckle tracking echocardiography for early detection of left ventricular systolic dysfunction and also for the relationship between myocardial deformation parameters and myocardial iron load which is measured by cardiac magnetic resonance relaxation time T2* values in asymptomatic children with beta-thalassemia major. Material and Methods: This multicenter cross-sectional study included 40 patients (mean age 15.4 ± 2.9, 42.1% male) and 40 healthy children whose age, gender, and body mass index-matched with patients. Each participant underwent conventional echocardiography and tissue Doppler imaging. Left ventricular ejection fraction; global longitudinal, circumferential, radial strains; twist; and torsion were measured by real-time three-dimensional and speckle tracking echocardiography. Cardiac magnetic resonance imaging T2* was measured in patients. Results: Left ventricular global longitudinal, circumferential, and radial strains were decreased despite preserved global ventricular function in patients compared to healthy children (p = p =.029, p = p