Iron homeostasis in vertebrates requires coordination between cells that export iron into plasma and those that utilize or store plasma iron. The coordination of iron acquisition and utilization is mediated by the interaction of the peptide hormone hepcidin and the iron exporter ferroportin. Hepcidin levels are increased during iron sufficiency and inflammation and are decreased in hypoxia or erythropoiesis. Hepcidin is a negative regulator of iron export. Hepcidin binds to cell surface ferroportin inducing ferroportin degradation and decreasing cellular iron export. Genetic disorders of iron overload of iron-linked anemia can be explained by changes in the level of hepcidin or ferroportin and of the ability of ferroportin to be internalized by hepcidin.