The pancreatic parenchyma was evaluated as a potential recipient site for hepatic fragment autotransplantation. Histologic and functional studies of hepatic autografts in the pancreas were performed in 15 mongrel dogs. Approximately 10 g of liver parenchyma was resected from each left lateral lobe. The remnant liver remained in situ. Bile secretion from the hepatic tissues implanted into the pancreas was estimated by measuring the indocyanine green (ICG)* concentration in pancreatic juice following intravenous ICG injection. One month following implantation, the hepatocytes in the pancreatic parenchyma were histologically colorless and did not have sinusoids. However, by the second month following implantation, hepatic nodules had grown extensively to become normal liver tissue, with sinusoids and a single liver cell-plate structure. At 4 months following intrapancreatic implantation the transplanted hepatic masses consisted of several hepatic lobules. Furthermore, ICG could be detected in the pancreatic juice of dogs surviving more than 2 months after implantation but no ICG could be detected in the pancreatic juice of normal controls. The present study provides direct evidence that hepatic grafts transplanted into the pancreas that has a ductal drainage system for bile secretion can reconstitute histologically normal liver tissue capable of secreting bile. This model can be used to understand the early steps of hepatic regeneration.