Objective To investigate the effect of B7-1 and IL-12 gene expression on the immunogenicity of hepatocellular carcinoma (HCC) HepG2 cells. Methods Plasmids encoding B7-1 and IL-12 molecules were retrovirally introduced into human HCC cells,empty vector as control. PBLs were cocultured with HepG2/B7-1,HepG2/IL-12 and HepG2/neo cells. Three days later,PBLs were submitted to specific cytotoxicity test and nonspecific cytotoxicity test against K562 cells by MTT assay.Results HLA-Ⅰ molecules on PBLs were detected by FACS.HLA-Ⅰ molecules expressing on PBL cocultured with HepG2/B7-1,HepG2/IL-12 cells were enhanced by 16.95% and 14.71% than those of HepG2/neo group, respectively(Ｐ＜0.05). Specific cytotoxicity against HepG2/B7-1 cells was 12.5% higher than that of against HepG2/neo cell,while no increase in that of against HepG2/IL-12 cells. Cytotoxicities against K562 cells in HepG2/B7-1,HepG2/IL-12 groups were 19.38% and 14.78% higher than those of HepG2/neo group, but no significant difference between the first two groups.Conclusion B7-1 and IL-12 gene transfer could remarkably promote immunogenicity of hepatocellular carcinoma cells and induce b specific and nonspecific immunity against hepatocellular carcinoma in vitro.