Objective:To study the influence of chemotherapy combined with thymopetidum on cellular immunity of patients with gastrointestinal malignant tumor in the later stage. Methods:80 cases were divided into two groups:testing group (40 cases,with thymopetidum and chemotherapy) and control group (40 cases,with chemotherapy only). 25 cases without malignant tumors were selected as normal group. The activity of T-lymphocyte subgroup and its cytokines as IL-2(Th1) and IL-10 (Th2) in peripheral blood of each group were investigated before treatment and at the tenth day after treatment of two weeks. Results:Before treatment,T-lymphocyte subset(CD3+,CD4+ and the ratio of CD4+/CD8+) and IL-2 of patients with gatrointestinal malignant tumor were lower than those of normal group(P < 0.05),while the values of CD8+ and IL-10 were higher obviously compared with normal group(P < 0.05). After treated for two weeks,CD3+,CD4+ and the ratio of CD4+/CD8+ were higher than those of before treatment in two groups(P < 0.05),and the changes in testing group were more obviously than those in control group(P < 0.05). In testing group,IL-2 was lower and IL-10 was higher than before treatment(P < 0.05),while there was no significant change after treatment in control group. The efficacy of testing group was higher than that of control group(P < 0.05). Conclusions:The immunity of T-lymphocyte subgroup was suppressed in the patients with gastrointestinal malignant tumor and the expression of Th2 type cytokines was enhanced. The cellular immunity of patients was improved by killing the tumor cells and removing the immunosuppressive agent after the chemotherapy together with Thymopetidum.