Despite present therapies of hypertransfusion and chelation of iron with desferrioxamine (DFO), patients with thalassemia major continue to succumb in their early to mid twenties to fatal iron overload, especially of the heart. Our laboratory has been involved in investigations of the use of tin-protoporphyrin (Sn-PP) as an adjuvent therapy for these patients. Sn-PP an analogue of heme, blocks microsomal heme oxygenase, and thus heme metabolism, thereby causing an increased excretion of intact heme (and with it iron) into the bile. Initial experiments using hypertransfused iron overloaded rats showed that Sn-PP, while having no effect upon total iron stores, caused a redistribtuion of iron, with significant decreases (up to 50%) in the iron content of the heart, kidneys and liver with corresponding increases in that of the spleen. Similar experiments done with splenectomized animals also showed decreases in the iron content of the heart with increases in liver iron. We conclude that Sn-PP does not cause a decrease in total iron stores, but it may cause a significant diversion/redistribution of iron from the heart to liver and/or spleen. We are now conducting experiments to determine whether Sn-PP given together with DFO leads to enhanced iron excretion.