Echocardiography is the modality of choice for detection of cardiac abnormalities in patients with β-thalassemia major which are the major causes of morbidity and mortality in these patients.This study was undertaken to study different echocardiographic findings in pediatric patients with β-thalassemia major, and to evaluate the feasibility of myocardial performance index in assessment of global ventricular function in these patients. Method: Thirty patients with B-thalassemia major with a mean age of 13.65±3.933 years (range 8 – 22years), as well as twenty age and sex matched controls, underwent to full history taking, clinical examination, and laboratory tests including Complete blood counts, serum ferritin evaluation. Complete M-mode and pulsed Doppler echocardiography were done for cases and controls to study cardiac dimensions as well as diastolic and systolic functions. Myocardial performance index (MPI) was calculated for both the left and right ventricles, and data were interpretated.Results: M-mode echocardiography revealed increased cardiac dimensions in thalassemia major cases as compared with control group. Out of thirty patients, diastolic dysfunction of the left ventricle was found in 4(13.33%) patients, while that of the right ventricle was found in 5(16.66%) patients. No significant difference in systolic functions between cases and controls were recorded. Impaired MPI of the left ventricle was found in 10 (33.33%) patients, while that of the right ventricle was impaired in 4(13.33%) patients.No significant correlation was found between left or right ventricular MPI level and any of the continuous variables in the studied cases including the serum ferritin level.Conclusion: Echocardiography is the modality of choice in cardiac assessment of pediatric patients with B-thalassemia major. Myocardial performance index, being has close correlation with the widely accepted systolic and diastolic hemodynamic parameters, is a useful method for the study of cardiac function in B- thalassemia patients. Further studies with larger number of cases are recommended.