BACKGROUND Thalassemia intermedia is a variety of beta thalassemia which shows clinical symptoms somewhere between asymptomatic carriers and thalassemia major. Cardiac dysfunctions due to chronic anemia and hemosiderosis are the major causes of death in these patients. The purpose of this study is to evaluate cardiac function in these patients by echocardiography. METHODS This case-control study was conducted on 22 thalassemic patients (mean: 16.5±5.8 years) and 66 healthy individuals (mean:16.07± 2.9years) as a control group from January 2007 to July 2008. There was no sign of cardiac involvement by physical examination, chest x-ray and ECG in patients. Echocardiographic parameters were measured in groups, and finally data was analyzed by SPSS software. RESULTS The mean of left ventricular myocardial performance index (MPI) (P-value=0.0001) and left ventricular mass index (LVMI) (P-value=0.0001) have statistically significant difference. Mean of interventricular septal dimension in diastole (IVSD), left ventricular posterior wall thickness in diastole (LVPWD), interventricular septal dimension in systole (IVSS) and left ventricular posterior wall dimension in systole (LVPWS) were also statistically significant with a P-value of, 0.002, 0.001, 0.01, 0.003, respectively. Aortic Pre-ejection period/Ejection time (PEP/ET) (P-value=0.009), ejection fraction (EF) (P-value=0.019), fractional shortening (SF) (P-value=0.041), left ventricular isovolumetric contraction time (ICT) (P-value=0.0001) and left ventricular isovolumetric relaxation time (IRT) (P-value=0.0001) were statistically significant. Mean of right ventricular MPI (P-value=0.0001) and IRT (P-value=0.0001) were also significantly different between two groups. Others echocardiographic parameters were not statistically significant (P-value>0.05). CONCLUSIONS Heart failures are earlier affected thalassemia intermedia patients compared with control group.