Copper deficiency in adult rats was induced by addition of silver chloride to the feed. The concentrations of silver, copper, iron, and zinc and relative activity of genes for copper transporting proteins and copper enzymes were measured in the cortex, cerebellum, hippocampus, amygdala, pituitary gland, and hypothalamus. Silver was accumulated only in the hypothalamic-pituitary system. These changes were accompanied by a decrease in the concentration of copper and increase in the contents of iron and zinc. Activity of genes for copper transport enzymes (high-affinity copper transporter; and two copper transport ATPases, ATP7A and ATP7B) and copper enzymes that were formed in the intracellular secretory pathway did not decrease in the brain of rats with copper deficiency. Relative activity of genes for intracellular copper enzymes (Cu(2+)/Zn(2+) superoxide dismutase and subunit IV of cytochrome c oxidase), concentration of immunoreactive polypeptides of superoxide dismutase, and enzymatic activity of superoxide dismutase remained unchanged under these conditions.