This article covers mouse cell lines showing the properties of hepatoblasts or oval cells and describes hepatocyte differentiation obtained from embryonic stem (ES) cells and mesenchymal adult progenitor cells. It considers the methods used for cultivation and differentiation of the cells, as well as the strengths and weaknesses of the different systems and perspectives for future research. Emphasis is given to hepatoblast cell lines because this is the material for which bipotentiality has been most clearly demonstrated and for which proliferation and differentiation conditions have been worked out.