Myocardial iron overload is a common finding in iron storage diseases like β-thalassemia. It is due to frequent transfusions and occurs despite chelation therapy. Cardiac complications (heart failure and arrythmias) lead to early death. MRI can offer a noninvasive index for heart iron deposition, before overt clinical and echocardiographic picture of heart failure takes place. Tissue iron is detected indirectly by the effects on relaxation times of ferritin and hemosiderin iron, interacting with hydrogen nuclei. Paramagnetic ferritin and hemosiderin iron shorten proton relaxation times, particularly T2 and T2*. Conventional MRI measurements are affected by iron excess, the instrumentation used, the applied field strength, the repetition time used in the imaging sequence, and other technical aspects. Myocardial T2* seems to be the most sensitive and easily reproducible index of myocardial iron deposition. However multicenter trials are needed for further evaluation of this technique.