Maintenance of iron balance is essential for humans and requires the coordinate regulation of iron transport into plasma from dietary sources in the duodenum, from recycled senescent red cells in macrophages, and from storage in hepatocytes. Hepcidin, a recently identified antimicrobial peptide produced in the liver, has been shown to play a central role in the homeostatic regulation of iron absorption and distribution [1]. It is a negative regulator of iron absorption in the small intestine and of iron release from macrophages engaged in the recycling of iron senescent erythrocytes [2]. The human hepcidin gene contains three exons that encode a 72-aa precursor (pro-hepcidin) with a characteristic furin cleavage site immediately N-terminal to the 25-aa major hepcidin species found in plasma and urine [3]. Recently, hepcidin has been shown to regulate iron homeostasis by interaction with ferroportin, an iron cellular exporter highly expressed in absorptive enterocytes, macrophages, hepatocytes, and placental cells [4].