Left ventricular filling patterns were assessed by Doppler echocardiography in 63 beta-thalassemia major patients, aged for to 21 years, with no clinical evidence of congestive heart failure and 63 age- and sex-matched normal controls. The patients with beta-thalassemia major were divided into three age groups, namely four to nine years (6.8 +/- 1.5 years), 10-15 years (12.1 +/- 1.6 years) and older than 15 years (17.3 +/- 1.7 years). They were compared with age- and sex-matched normal controls in respects of Doppler diastolic indices. The ratio between the early and late (atrial) peaks of flow velocity was higher and peak flow velocity in late diastole was significantly lower in patients with beta-thalassemia major as compared to controls in all three age groups (p < .001). As compared with the controls, peak early diastolic flow velocity was also significantly higher in the thalassemics aged 10 to 15 years (92 +/- 16 vs 80 +/- 12 cm/s, P < .01) and in those older than 15 years (95 +/- 16 vs 79 +/- 13 cm/s, p < .001). Restrictive left ventricular diastolic abnormalities were detected in a total of 34 (54%) patients with beta-thalassemia major, whereas left ventricular systolic abnormalities were identified only eight (13%) of them. None of the patients without left ventricular diastolic abnormalities showed left ventricular systolic abnormalities. There was not any significant correlation between the hematologic parameters, such as mean serum ferritin, maximum serum ferritin and the number of blood units transfused, and left ventricular Doppler diastolic indices (p > .05). From the data presented here, we therefore conclude that left ventricular diastolic abnormalities develop in patients with beta-thalassemia major in the early phase of the disease and before the appearance of systolic abnormalities, when clinical symptoms of congestive heart failure are absent.