Iron is an essential trace element in mammalian metabolism. Body iron stores require a tight regulation to avoid detrimental effects due to iron excess or to iron deficiency. Iron losses being not adaptable, iron balance is controlled only through intestinal iron absorption which is regulated by the hepatic peptide hepcidin. Hepcidin synthesis is controlled by several genes including the HFE, hemojuvelin and transferrin receptor 2 genes. Mutations in these genes lead to a phenotype of hemochromatosis. Recently, the bone morphogenetic protein 6 was shown to be the key endogenous ligand involved in the cascade regulating hepcidin synthesis.