The aim of this study is to establish a novel mouse model with high achievement and chimerism by in utero transplantation of human hematopoietic stem/progenitor cells and to explore the possibility that human adult hematopoietic stem/progenitor cells can differentiate into hepatocyte-like cells and partially repair the liver damage induced by carbon tetrachloride (CCl(4)). Mononuclear cells (MNCs) were isolated from fresh human umbilical cord blood (hUCB) and CD34(+) cells were enriched from the MNCs by magnetic cell isolation. These cells were injected respectively into the fetal mice at 11-13 days of gestation. At one month after birth, the specific markers of human cells, human alpha-satellite sequence (h17alpha), CD14, CD34, CD45, and GPA were detected by PCR and FACS. At three and six months after birth, the established human-mouse chimeras were administered with CCl(4) by intraperitoneal injection. The biochemical markers (ALT, AST, ALP, albumin) in serum were determined and human hepatocyte-specific proteins, such as human albumin, hepatocyte nuclear factor-4, hepatocyte-specific antigen, tryptophan 2,3-dioxygenase and alpha fetoprotein were analyzed by PCR, RT-PCR, real-time PCR and immunohistochemistry staining, respectively. More than 77% of recipients demonstrated human-mouse chimera. Significantly, hUCB hematopoietic stem/progenitor cells may differentiate into human hepatocyte-like cells with evidence of the expression of human hepatocyte-specific proteins as well as partially repair or protect liver damage induced by CCl(4). The mouse model described in this article provides a useful tool for the studies of regeneration of human hepatocyte-like cells from adult hematopoietic stem/ progenitor cells as well as facilitates the therapeutic potential for liver diseases or damage by in utero transplantation.