To establish the efficacy of cell therapy in Wilson's disease, we used the Long-Evans Cinnamon (LEC) rat model with atp7b gene mutation and copper toxicosis. Several groups of LEC rats were established, including animals pretreated with retrorsine to exacerbate copper toxicosis and inhibit proliferation in native hepatocytes followed by partial hepatectomy to promote liver repopulation. Hepatocytes from normal, syngeneic LEA rats were transplanted intrasplenically. Animal survival, biliary copper excretion, and hepatic copper were determined. The magnitude of liver repopulation was demonstrated by measuring serum ceruloplasmin and hepatic atp7b mRNA. Long-term survival in LEC rats treated with retrorsine, partial hepatectomy, and cell transplantation was up to 90%, whereas fewer than 10% of animals pretreated with retrorsine, without cell therapy, survived, P < 0.001. Liver repopulation occurred gradually after cell transplantation, ranging from <25% at 6 weeks, 26 to 40% at 4 months, and 74 to 100% at 6 months or beyond. Liver repopulation restored biliary copper excretion capacity and lowered liver copper levels. Remarkably, liver histology was completely normal in LEC rats with extensive liver repopulation, compared with widespread megalocytosis, apoptosis, oval cell proliferation, and cholangiofibrosis in untreated animals. These data indicate that liver repopulation with functionally intact cells can reverse pathophysiological perturbations and cure Wilson's disease.