These studies are designed to evaluate the clinical benefits achieved by iron chelation in patients with chronic iron overload. Desferrioxamikne is administered by subcutaneous infusion and iron removal is determined by quantitation of urinary iron excretion and careful recording of the total iron administration by transfusion. Those patients who have no evidence of cardiac disease are randomized to receive either ascorbic acid (3 mg/kg) or placebo. Sixty-five patients are now included in our long term chelation trial and of these 49 have been randomized to the ascorbic acid study. Most patients have now been followed for a minimum of three and many for four years. Currently all patients are undergroing an annual evaluation with the expectation that we will analyze all data in an effort to judge the clinical efficacy of chelationand the influence of ascorbic acid therapy.