This review of the copper-iron interaction in Wilson's disease was mainly based on ten patients (three females and seven males) studied in our institutes because the genetic tests of ATP7B for Wilson's disease of primary copper toxicosis and HFE for hemochromatosis, the biochemical parameters of copper and iron, and morphological studies on biopsied liver specimens were complete. All patients had hypoceruloplasminemia and hepatic lesions compatible with Wilson's disease. One patient was homozygous and nine patients were compound heterozygous for the mutations in ATP7B, and all patients were free from the major mutation, C282Y, of HFE. The biochemical parameters of iron metabolism were not specific, except for serum ferritin concentration. Judging from the traditional criteria, seven patients had hyperferritinemia. Histochemical iron was stained in the livers of seven patients and histochemical copper was found in nine patients. Microanalysis was more sensitive than histochemistry, detecting copper and iron accumulation in the hepatocellular lipofuscin particles of all patients. Using an improved fixative, intralipofuscin distribution was found to be different between cuprothionein and iron complexes. Iron overload in Wilson's disease might be worsened after treatment because of the close relation to hypoceruloplasminemia, in which the iron efflux from the liver to the circulation is disturbed.