Determinations of tissue copper concentrations were made on autopsy specimens from 2 patients with Wilson''s disease and 4 control subjects. Higher copper levels in the tissues from Wilson''s disease patients were found; this was particularly notable in the liver, brain, kidney, and cornea. Neither in patients with hepatic disorder nor in patients with blood disease was there a similar degree of copper deposition in tissues. In the patients with Wilson''s disease, the brain cortex contained a slightly higher copper level than the basal ganglia, but the latter demonstrated more prominent histologic changes than the former. It is suggested that the lower resistance to the copper accumulation in the basal ganglia might be responsible for these changes. The copper-removing therapy employed in the 2 Wilson''s disease patients appeared to be without influence on the CNS copper concentration, but it may have reduced the copper content of the liver and kidney. The correlation between the supernormal tissue copper levels and the clinical findings indicates that the biochemical lesions which typify Wilson''s disease are not confined to the lenticular nucleus and the liver but actually may involve the entire central nervous system and several organs.