Objective To investigate the function of hepatocyte nuclear factor 6（HNF 6） during the development of intrahepatic biliary. Methods The expression of HNF6 at different stages of intrahepatic bile ducts embryonic development and in the adult mouse liver were detected by RT-PCR and immunohistochemical staining. Results RT-PCR results showed that the expression of HNF6 was detected in the liver at E9d, the time of liver formation onset. Then, HNF6 disappeared transiently at E13d, but it appeared again at E15d. Its expression lasted till birth. According to the immunohistochemical staining studies, the immunohistochemical positive reaction of CK19, which dispersed in the liver cords, appeared at E13d. At E15d, CK19-positive cells formed a single cell layer called the ductal plate around the branches of the portal vein located close to the hilum. Later, these immunohistochemical positive cells were confined to the ductal plate and biliary epithelial cells. The immunohistochemical positive reaction of HNF6 was detectable in most cells of liver cords at E9-11d, which became undetectable at E13d. Similar to CK19 at E15-17d, the immunohistochemical positive reaction of HNF6 could be observed at P1d. BR>Conclusion HNF6 has no important role in the specification of liver during rat embryonic development. It may play a role in the onset of liver development, the differentiation of hepatic stem cell towards biliary epithelial cells and the maintenance of the morphological characteristic of biliary epithelial cells. BR>