Objective To investigate the expression of exogenous γ-interferon gene in human hepatocellular carcinoma cells following retroviral transduction and the effect on the expression of surface HLA class Ⅰ molecules.Methods Retroviral vector pLXSN was used to introduce human γ-interferon (IFN-γ) gene into four different human hepatocellular carcinoma cell lines (HCC). The G418-resistant colonies were isolated and cloned. The integration and expression of IFN-γ gene were determined by PCR and RT-PCR analysis. A bioassay method was used to test the amount of IFN-γ secreted by gene modified HCC cells. The expression of HLA class Ⅰ molecules in HCC cells were analyzed by flow cytometry using indirect fluorescence staining.Results Four different HCC cell lines were successfully transduced with human IFN-γ gene using retroviral vector. The integration and expression of IFN-γ gene were shown only in the transduced cells. All four genetically modified HCC cells can secrete varied amount of IFN-γ and demonstrate a significant up-regulation of surface HLA class Ⅰ antigens. One specific HLA class Ⅰ antigen, HLA-A2, has almost the same degree of increase as that of the total HLA class Ⅰ molecules after transduction with IFN-γ gene.Conclusions Gene modification with IFN-γ gene can significantly enhance the expression of HLA class Ⅰ molecules in HCC cells and may increase its immunogenicity. These gene modified tumor vaccines can be helpful in tumor biotherapy.