The emergence of cells with hepatocellular properties in the adult pancreas has been described in several experimental models. To determine whether adult pancreas contains cells that can give rise to therapeutically useful and biochemically normal hepatocytes, we transplanted suspensions of wild-type mouse pancreatic cells into syngeneic recipients deficient in fumarylacetoacetate hydrolase and manifesting tyrosinemia. Four of 34 (12%) mutant mice analyzed were fully rescued by donor-derived cells and had normal liver function. Ten additional mice (29%) showed histological evidence of donor-derived hepatocytes in the liver. Previous work has suggested that pancreatic liver precursors reside within or close to pancreatic ducts. We therefore performed additional transplantations using either primary cell suspensions enriched for ducts or cultured ducts. Forty-four mutant mice were transplanted with cells enriched for pancreatic duct cells, but only three of the 34 (9%) recipients analyzed displayed donor-derived hepatocytes. In addition, 28 of the fumarylacetoacetate hydrolase-deficient mice were transplanted with cultured pancreatic duct cells, but no donor-derived hepatocytes were observed. Our results demonstrate for the first time that adult mouse pancreas contains hepatocyte progenitor cells capable of significant therapeutic liver reconstitution. However, contrary to previous reports, we were unable to detect these cells within the duct compartment.