ICL670 (deferasirox) is an orally active iron chelator, intended as once daily mono-therapy for the treatment of transfusional iron overload, which has undergone extensive multi-centre Phase II and Phase III trials. Data from such studies suggest that 20mg/kg as a single daily dose will achieve iron balance in the majority of transfusionally dependent patients, whereas 30mg/kg/day typically achieves negative iron balance (Cappellini, Abstract 3619, ASH 2004) (Porter, Abstract 3193, ASH 2004). Patients with transfusion dependent anaemia and iron overload who were entered into these multi-centre studies at UCL Hospitals had myocardial T2* CMR performed at the Royal Brompton Hospital, as part of their routine monitoring, in line with previous clinical management at our centre. Study 108, a non-randomized study, included poorly chelated patients with -thalassemia and other iron overload conditions receiving regular blood transfusion: all patients received 10-30mg/kg/day of ICL670. Study 107 consisted exclusively of transfusion dependent -thalassemia patients, randomized to receive either 8–10h sc DFO (30–50mg/kg/day) or ICL670 (10–30mg/kg/day) with doses stratified for baseline liver iron concentration (LIC). We report here changes in cardiac T2*, LIC and serum ferritin, as well as LVEF in all patients on these two studies treated at UCLH for a mean of 13.1± 0.78 months, in whom CMR was obtained. In a total of 23 patients treated with ICL670, mean age 24.6y (range 9–50y), 18 with transfusion dependent -thalassaemia and 6 other iron overload conditions (2 Pyruvate kinase deficiency, 2 sideroblastic anemia, 2 Diamond Blackfan Anemia), myocardial T2* improved significantly from a pre-treatment geometric mean of 18.0ms to 23.1ms (p = 0.013, paired student t test). In the same patients, serum ferritin fell significantly from 3173 ±410 μg/L to 2451 ±242μg/L (p= 0.023, paired student t test) and LIC fell significantly from 18.3 ±2.2 mg/g dry wt to 10.0 ±1.49 (p= 0.0002, paired student t test). There was no significant change in LVEF before or after treatment over the same period. Patients treated in the DFO arm of study 107 (n=8) also showed a small non-significant increase in myocardial T2* from 18.1 ms to 21.1 ms (p= 0.11), These studies suggest that once daily mono-therapy with ICL670 will be effective at improving myocardial T2* and by inference myocardial iron loading in a wide range of patients with transfusional iron overload. Prospective randomised controlled studies in larger patient numbers are now indicated.