Since the development of a method for isolating primary hepatocytes by collagenase perfusion, many investigators have demonstrated the efficacy of hepatocyte transplantation in the treatment of liver failure and inherited metabolic disorders in experimental animals. Treatment of liver diseases with transplantation of isolated hepatocytes rather than the whole liver has several theoretical advantages. Unlike the whole liver, isolated hepatocytes could be cryopreserved for instant availability and could be modified genetically or otherwise to enhance specific functions, stimulate proliferation or abrogate allograft rejection. Hepatocyte transplantation should be less stressful than whole liver transplantation because the host organ remains intact. Since the transplanted cells integrate into the host liver, they could provide restorative potential and the consequences of graft loss would be relatively minor. In addition, hepatocyte transplantation would not interfere with subsequent liver transplantation, should that become necessary.