Abstract: Objective To investigate the effect of cytokineinduced killer (CIK) cells immunotherapy on immunity function of non-small cell lung cancer (NSCLC) patients after operation. Methods Fifty patients with histological or cytological diagnosis of NSCLC on Ⅰstage,Ⅱstage andⅢa stage of tumor, nodes, metastasisclassification were randomly divided CIK cells therapy group and conventional therapy group, 25 cases each group. The immunity function of patients with NSCLC, including the levels of CD3+, CD4+ T cells, ratio of CD4+/CD8+, natural killer(NK) cells, and the levels of Th1/Th2 cytokine were detected before treatment, and the 2nd, 4th, 8th week after treatment. Results The levels of CD3+, CD4+ T cells, NK cells, ratio of CD4+/CD8+, interleukin-2(IL-2), interferon-γ(INF-γ) in CIK cells therapy group at the 2nd week after treatment were more higher than those before treatment (Plt;0.01), their levels reached the peak at 4th week, from then on, it began to decrease. Meanwhile, the levels of Th2 of CIK cells therapy group began to decrease at the 2nd week after treatment, a low ebb at 4th week. At the 2nd, 4th and 8th week,the levels of CD3+,CD4+ T cells, ratio of CD4+/CD8+, NK cells,IL-2, INF-γ, interleukin-4(IL-4), interleukin-10(IL-10) of CIK cells therapy group compared with those inconventional therapy group,there were statistical significance difference［(Plt;0.05),at 4th week after treatment, CD3+ 70.2%±9.1% vs.46.3%±5.8%; CD4+40.2%±7.1% vs.22.9%±4.5%; CD4+/CD8+ 1.82±0.43 vs. 1.09±0.34; NK 15.7%±5.4% vs.10.5%±2.5%; IL-2 34.8±11.7 ng/L vs. 19.8±12.1 ng/L; INF-γ63.7±23.3 ng/Lvs. 30.8±10.6 ng/L; IL-4 10.2±8.6 ng/L vs. 25.8±6.3 ng/L; IL-10 10.6±3.4 ng/L vs. 21.4±8.6 ng/L］. Conclusion The results indicate that CIK cells immunotherapy can enhance the immune function of NSCLC patients after operation.