Silver ion causes a number of toxic effects, it decreases the activities of lactate dehydrogenase and glutathione peroxidase, and the peroxidation of membrane lipids. Silver ions complex strongly to sulfhydryl groups and the effects of preinduction of metallothionein, a sulfur-rich protein, on silver administration in rats were examined. The preinduction of metallothionein decreased the mortality of mice following silver administration. A major portion of the incorporated silver in the liver was bound to the basal membrane and cellular components, and the distribution of silver into cytosol was small. The preinduction of metallothionein decreased the amount of bound silver in the membrane and increased the distribution of silver in the cytosol; in addition, it depressed silver-induced lipid peroxidation in liver.