The potential of embryonal day 14 (ED) fetal liver epithelial progenitor (FLEP) cells to repopulate the normal and damaged liver was studied throughout a 3-month period in syngeneic mice. In normal liver, FLEP cells proliferated and differentiated into hepatocytes after transplantation, and liver repopulation was moderate (5%-10%) after 3 months. In diethylnitrosamine-treated livers FLEP cells continued to proliferate at 3 months after transplantation; both the number and size of clusters derived from FLEP cells gradually increased throughout time. Transplanted cells proliferated and differentiated into both hepatocytes and bile ducts to produce extensive liver repopulation (30%-50%). This report showed that isolated fetal liver epithelial cells exhibit bipotential properties of stem cells, which can engraft, proliferate, and differentiate into hepatocytes and bile duct epithelial cells with high repopulation capacity in the injured liver.