The various roles played by copper in iron metabolism are reviewed. Copper may interfere with iron absorption by binding to mucosal transferrin. Mobilization of iron from mucosal, reticuloendothelial, and hepatic parenchymal cells may be effected through the action of ceruloplasmin. Copper may also participate in heme synthesis through the action of cytochrome oxidase. Reutilization of iron by the spleen reticuloendothelial cells is subjected to inhibition by excess copper.