A recombinant eukaryotic expression vector containing HSA(Heat-stable Antigen) cDNA and PcDNA 3 plasmid was constructed and then transfected into mouse lymphoma cell line---EL-4 by electroporation. The transfected tumor cells were selected in RPM11640 containing G418 (400?g/ml).HSA expression was detected by FACS using indirect immunofluorescene technique with HSA mAb (Ml/69).To obtain high expression of HSA'EL-4 cells ,the transfected cells were recloned by limiting dilution. In animal experiments, we found that the tumorigenicity of HSA+ EL-4 is weaker than HSA- EL-4(EL-4 or EL-4-v). The size of HSA+ EL-4 tumors were significantly smaller than that of HSA- EL-4 tumors. The tumor growth speed and survival time of tumor-bearing mice are also different. A protective effect against the subsequently challenge with low dose (2 ? 1 03/mouse) wild type tumor cells was found in immunized mice with inactivated HSA+ EL-4 tumor cells but not in those animals immunized with HSA- EL-4 tumor cells. Moreover, HSA+ EL-4 could be used as tumor vaccine to cure the established tumor at the initial stage.