O1igodendrocytes are known to be responsible for the synthesis and maintenance of myelin sheath in the central nervous system, and their functional disturbance leads to defect in myelination. But, the fine mechanism of myelination by oligodendrocytes is not yet known, and iron metabolism in central nervous system is suspected to be related with myelination process by oligodendrocytes. Carbonic anhydrase-II[CA-II], transfe-rrin, and ferritin are known to be present at oligodendrocytes and suspected to play a role in iron metabolism of central nervous system. In this study, demyelination and remyelination of ICR mouse brains were induced using cuprizone, the copper-chelating agent, and immunohistochemical changes of CA-II-, transferrin-, and ferritin-immunoreactive oligodendrocytes at corpus callosum were observed. During demyelination by cuprizone feeding, the numbers of CA-II- and transferrin-immunoreactive oligodendrocytes were decreased. Especially, the decrease ratio of CA-II-positive cells was great. In contrast, the number of ferritin-positive oligodendrocytes was increased during demyelination by cuprizone feeding. Cessation of cuprizone feeding leaded remyelination and the numbers of CA-II-, transferrin-, and ferritin-immunoreactive oligodendrocytes were returned to normal level. In conclusion, the derangement of iron metabolism in oligodendrocytes may be related to demyelination mechanism of central nervous system, and the CA-II is suspected to have an important role in iron metabolism of oligodenrocytes in relation to demyelination and remyelination induced with cuprizone.