Subjects with thalassemia major require regular transfusion therapy to sustain life. The iron present in the transfused blood remains in the body where it can cause a variety of organ dysfunctions. Lifelong iron chelation therapy is needed to maintain iron balance but its effectiveness varies greatly. Like that of deferoxamine (Desferal, DFO) the mainstay of chelation therapy for 30 years, the effectiveness of deferasirox (Exjade, ICL670), the newly approved, orally effective iron chelating drug, is not satisfactory in all subjects. Even with good compliance, the iron excretion induced by a given drug exhibits wide subject-to-subject variability. There is often persistent iron overload of extra hepatic tissues such as the heart and pancreas leading to cardiac disease and diabetes. Combining the drugs may be a better approach in those subjects at increased risk. The iron balance studies proposed will permit an assessment of the potential of such a combination to place subjects in net negative iron balance and the relative effectiveness of the combination in relation to that of the individual drugs, an additive effect being expected. With such information, physicians will be able to design individualized chelation regimens that maximize effectiveness while minimizing side effects by adjusting the ratio and/or the dosing schedule of the two drugs.