Objective: To investigate the cellular immunity response in vitro and the tumorigenecities in vivo of mB7-1 gene transfected murine ovarian cancer cell line. Methods: mB7-1 gene was transfected into the NuTu-19 cell line by retrovirus vector, and the expression of mB7-1 gene was confirmed by flow cytometry(FCM).NuTu-19/neo and NuTu-19/mB7-1 cells were injected subcutaneously into syngeneic Fischer 344 rats respectively, and their tumorigenecities were recorded. Proliferation indices of lymphocyte were assayed after syngenieic mixed tumor-lymphocyte cultures(MTLCs). The lysis activity of CTL toward tumor cells was determined using methyl thiazolyl tetrazolium(MTT) assay. Results: Successful transfection of mB7-1 gene into NuTu-19 cell line was comfirmed with FCM. In vitro study showed that there was no obvious changes in cell growth of gene transfected cell line, compared with the cell line NuTu-19. NuTu-19/mB7-1 cells could induce more effective proliferation of effector lymphocytes( P ＜ 0.05). The lysis activity of CTL activated by NuTu-19/mB7-1 was stronger than that of NuTu-19/neo ( P ＜ 0.01). Tumor sizes were smaller in the NuTu-19/mB7-1 receptance syngeneic Fischer 344 rats compared with those in the control group. Conclusion: mB7-1 genetically modified ovarian cancer cells could induce the cellular immunity response in vitro and the tumorigenecitiy of NuTu-19 cells was decreased after inoculation with the experimental vaccine.