Hereditary hemochromatosis (HH) is an inherited iron overload disorder characterized by normal iron-driven erythropoiesis and abnormal iron metabolism, leading to excess iron deposited in parenchymal cells of liver, heart, and endocrine glands. Iron hormone, hepcidin, plays a critical role in iron homeostasis through interaction with ferroportin (FPN), a major cellular iron exporter. Hepcidin is encoded by hepcidin antimicrobial peptide (HAMP). Mutations in hepcidin and any genes that regulate the biology of hepcidin, including hemochromatosis genes (HFE), Hemojuvelin (HJV), transferring receptor 2 (TFR2) and FPN, result in hemochromatosis. The identification of hepcidin and its role will provide a better understanding for pathogenesis of HH.