Effects of chelators on the copper(Cu) therapy for the mutant mouse, Macular, which is a model animal of Menkes' disease were studied. Simultaneous administration of some chelators reduced the necessary dose of Cu (10 mg/kg) for the survival of the mice to one tenth. By this treatment the Cu concentration in the brain was increased but Cu in the kidney was not increased as much as Cu administration without chelator. Surviving mice showed normal growth in terms of body weight and fertility. Furthermore same effects were observed even when the chelator was administered without Cu. In the chelators tested, derivatives of carbamic acid like dimethyldithiocarbamate, which forms a lipophilic complex with Cu, were effective.