Hepatocytes have the unique capacity to self-renew and repair the liver ad integrum when stimulated to proliferate by liver injury. However, transplantation of isolated hepatocytes is usually not sufficiently efficient for therapeutic purposes. We conferred a survival advantage on transplanted hepatocytes and showed that they were able to repopulate almost the entire mouse liver after repeated injury. In contrast, we found that bone marrow stem cell transdifferentiation was inadequate for therapeutic liver regeneration. Current data on liver stem cells will be discussed.