Hereditary hemochromatosis (HH) is a genetic metabolic disease characterized by increased intestinal iron absorption and progressive iron loading in the cells of various organs. Human body iron homeostasis involves a number of complicated processes, some of which are not identified yet. Genetic analysis of patients affected by HH recently led to the discovery of many novel proteins and mechanisms that can influence the uptake, transport, storage, and excretion of iron. It also showed that hemochromatosis is a very complex disease and that the type of mutation can influence its clinical manifestation. This review presents the current knowledge about the mechanisms of iron metabolism and describes the types of hereditary hemochromatosis and the mutations which induce the disease.