We used immunohistochemical studies to demonstrate that transferrin (the iron mobilization protein) and ferritin (the iron storage protein) are specifically localized in oligodendrocytes in gray and white matter of the human central nervous system. In addition, iron is also localized predominantly in oligodendrocytes. Oligodendrocytes have been well established as the cells responsible for myelin production in the central nervous system. The results of this study suggest that oligodendrocytes (or a subpopulation of oligodendrocytes) might have the additional function of mediating iron mobilization and storage in the central nervous system.