Objective　To evaluate the effect of inducing differenation of all trans retinoic acid (ATRA) on immunologic function of patients with gastric cancer. Methods　T-lymphocyte subsets(T-Ls) and interleukin-2 receptor(sIL-2R) of 56 patients with gastric cancer after treatment of ATRA were studied. Results　In radical gastric cancer resection group, the serum CD3,CD4 and CD4/CD8 rate were higher and sIL-2R were lower than those in the control group, after treatment of ATRA, CD3,CD4 and CD4/CD8 rate and sIL-2R were as high as those in the control group. In the non-operative or palliative gastric resection group, CD3,CD4 and CD4/CD8 rates were increased markedly and the serum sIL-2R was decreased significantly than those in the control group. Conclusion　ATRA inducing differenation can improve the immunity of the patients with gastric cancer.