Thalassemia major is a severe and transfusion-dependent anemia that occurs in persons homozygous for a mutation that affects the capacity for synthesis of the beta-globin subunit of hemoglobin. Characterization of the molecular defects that cause beta-thalassemia is providing insight into the mechanism of globin gene regulation. Newer approaches to the management of thalassemia major include more effective chelation by use of subcutaneous desferrioxamine and attempts to obtain young erythrocytes with a longer potential for survival in recipient patients. Development of more effective chelators that may be given orally is an ongoing effort. Noninvasive evaluation of cardiac structure and function in patients with thalassemia major suggests that myocardial iron deposits begin at an early age, causing functional impairment long before the onset of clinical symptoms. Prevention or reversal of these cardiac abnormalities remains the goal of chelation therapy.