Iron-induced cardiac disease is the primary cause of death in transfused patients with thalassaemia major. The beneficial effects of deferoxamine mesylate on clinical cardiac disease have been well described but the impact of therapy on subclinical cardiac dysfunction is unknown. To assess the reversibility of subclinical cardiac dysfunction we studied the cardiac status during iron depletion treatment (phlebotomy) in iron overloaded patients, cured of thalassaemia by marrow transplantation, without clinical manifestation of heart failure but with alteration in both left ventricular diastolic function and in contractility property. 32 patients were studied and demonstrated a slight but significant impairment in the morphology and function if compared with matched normal controls. 17 of these patients were submitted to sequential echocardiographic evaluations during the phlebotomy programme. Following completion of the programme, normalization of the indices of contractility and normalization of diastolic function were observed. This study indicates that transplanted thalassaemia patients with subclinical left ventricular diastolic dysfunction and impaired left ventricular contractility may reverse these processes with an effective regimen of iron reduction such as phlebotomy.