Objective: To investigate the anti-gastric cancer (GC) effect of LAK cells induced by TNFα with IL-2 and the influences of pretreatment with TNFα on the susceptibility of GC cells to LAK. Methods: Induced by TNFα combined with IL-2 at different concentrations, blocked by TNFα McAb, and after pretreating the GC cells with TNFα, LAK cytotoxicity to GC cells was detected by LDH colometric assay. Results: At low concentrations of IL-2, TNFα increased the cytotoxicity of LAK and the concentration of IL-2 necessary to induce the cytotoxicity to the same extent decreased 10 folds. Pretreatment of GC cells with TNFα made the cytotoxicity of LAK to the GC increase by 9%. Conclusion: TNFα increased the cytotoxicity of LAK induced by IL-2 to GC cells, and the GC cells pretreated with TNFα were more susceptible to LAK.