Sixty-three cases with stomach cancer were randomized and observed, the results showed that the count of T lymphocytes in chemotherapy combined with Shenmai injection (SMI) group increased, while in control group it decreased, the difference was significant (P < 0.05). The results also indicated that the count of OKT4 cells and the ratio of OKT4/OKT8 decreased after chemotherapy, but in SMI group both parameters increased in advence which were higher in the 4th week after chemotherapy than that before chemotherapy. However, the count of OKT1 cells and the ratio of OKT4/OKT8 were still in low level. Serum interleukin-2 receptor (sIL-2R) level also decreased (P < 0.05), while activities of natural killer cell (NK) and lymphokine activated killer cell (LAK) level increased (P < 0.05) in SMI group. Although the sIL-2R level had no change, both NK and LAK level decreased in control group. In addition, the difference of IgA, IgM, IgG level were not significant between these two groups. This suggested that SMI might improve human immune function to facilitate the chemotherapy of patients with stomach cancer.