Abstract: Objective　To evaluate the changes and clinical implication of cell immune function in gastric cancer patients before and after operation.Methods　T lymphocyte subsets and natural killer(NK) cell activity of 56 cases of gastric cancer and 38 cases of normal subjects were measured by monoclonal anti-human T lymphocyte antibody and MTT-assay before and after operation.Results　It was found that CD+3、CD+4、 ratio of CD+4/CD+8 and NK cell activity were significantly lower, but CD+8 cell was higher in preoperative gastric cancer patients than those of the control group (P<0.01). The cell immune function gradually recovered 20 days after operation. There was significant difference before and after operation (P<0.05). No significant differences CD+3、CD+4、ratio of CD+4/CD+8 and NK cell activity were found between Borrmann Ⅰ、Ⅱ and Ⅲ、Ⅳ,lympy nodal metastasis positive and negative gastric cancer patients.Conclusion　Cell immune function in patients with gastric cancer was relates to tumor progress and T lymphocyte subsets and NK cell activity could be used as important monitoring indicators.