Oncolysates, debris of tumor cells, have been proven to be effective in active immunotherapy of cancer. In this experiment, the oncolysates from murine melanoma cells B16-F10 transfected by recombinant vaccinia viruses encoding human IL-2(IL-2VBO) were used as vaccine. After treatment of tumor bearing mice with pulmonary metastases by intravenous injection of IL-2VBO or rVV-IL-2, higher level IL-2 activity was detected in the serum of IL-2VBO or rVV-IL-2 treated mice at 8h. Further experiment results demonstrated that IL-2VBO significantly reduced the number of pulmonary metastases and prolonged the survival time of tumorbearing mice when compared with other preparations. Fresh peripheral blood lymphocytes from IL-2VBO treated mice showed potent cytotoxicity to BI6-F10 cells and YAC-1 cells. But only cytotoxicity to B16-F10 cells is more marked than that in rVV-IL-2 group, indicating that the IL-2VBO could induce specific and non specific anti-tumor immunity. Because IL-2 expression was at the same level in the serum of IL-2VBO or rVV-IL-2 treated mice, the results suggested that the specific anti-tumor immunity induced by IL-2VBO might contribute to the enhanced therapeutic effect of IL-2VBO.