Objective: To assess the effect and mechanism of compound Xiansu capsule (仙酥胶囊, XSC) combined with chemotherapy in treating gastric carcinoma of mid late stage. Methods: Sixty one patients of the test group were treated by XSC combined with chemotherapy and 30 patients of the control group treated with chemotherapy alone. The effect of treatment and cell mediated immunity of patients were observed. Results: The effective rate of the test group and the control group was 32.8% and 13.3% respectively ( P <0.05), the toxic reaction occurrence caused by chemotherapy was less in the former than that in the latter group ( P < 0.01). The CD 8 level of patients in the test group decreased, and CD 4/CD 8 level was raised obviously, which suggested that XSC had immuno regulating effect on T cell. Conclusion: XSC could enhance the efficacy and reduce the toxic and side effect of chemotherapy. To regulate the cell mediated immunity of patients is possibly its mechanism. Method: Sixty one patients of the test group were treated by XSC combined with chemotherapy and 30 patients Objective: To assess the effect and mechanism of compound Xiansu capsule (Xiang Capsule, XSC) combined with chemotherapy in treating gastric carcinoma of mid late stage. Of the control group treated with chemotherapy alone. The effect of treatment and cell mediated immunity of patients were observed. Results: The effective rate of the test group and the control group was 32.8% and 13.3% respectively ( P <0.05), the toxic The reaction was caused by chemotherapy was less in the former than that in the latter group ( P < 0.01). The CD 8 level of patients in the test group decreased, and CD 4/CD 8 level was raised obviously, which suggested that XSC had Immunoregulated effect on T cell. Conclusion: X regulates the efficacy and reduce the toxic and side effect of chemotherapy. To regulate the cell mediated immunity of patients is possibly its mechanism.