Abstract: Objective To investigate the effect of cytokine-induced killer(CIK) cells therapy on T cell subsets in the peripheral blood and general condition of non-small cell lung cancer (NSCLC) patients. Methods Peripheral blood mononuclear cells (PBMCs) were collected from the peripheral blood of NSCLC patients. CIK cells were expanded by classical protocol, re-infused to the patients once a day for 3 consecutive days. Before and after 3 courses of CIK cells therapy, the changes of T cell subsets were assessed by flow cytometry, and the difference of T cell subsets between patients and healthy subjects were analyzed. General condition of NSCLC patients was observed before and after the therapy. Results Compared with the control group, the expression of CD3⁺T cells, CD3⁺CD4⁺T cells, CD4⁺/CD8⁺ T cells in the peripheral blood of NSCLC patients were significantly decreased (P<0.05), the expression of CD3⁺CD8⁺ T cells were significantly increased (P<0.05). After the CIK cells therapy, the expression of CD3⁺ T cells, CD3⁺CD4⁺ T cells, CD4⁺/CD8⁺ T cells were significantly increased (P<0.05); while the expression of CD3⁺CD8⁺ T cells were significantly decreased (P<0.05). Compared with the control group, the expression of CD3⁺ T cells and CD4⁺/CD8⁺ T cells were significantly decreased (P<0.05) after CIK cells therapy; the expression of CD3⁺CD4⁺ T cells and CD3⁺CD8⁺ T cells were increased (P>0.05). Tregs in NSCLC patients before CIK cells therapy were significantly increased compared with the control group (P<0.05), and Tregs in stage Ⅲ~Ⅳ patients were significantly higher than that in stage Ⅰ~ Ⅱ patients(P<0.05). After CIK cells therapy, Tregs in stage Ⅰ~ Ⅱ and stage Ⅲ~Ⅳ patients were significantly decreased compared with those before CIK cells therapy(P<0.05). After CIK cells therapy, Tregs in stage Ⅰ~ Ⅱ patients were significantly lower than that in the control group (P<0.05).Tregs in stage Ⅲ~Ⅳ patients were still higher than that in the control group(P>0.05). Conclusion CIK cells therapy could enhance the immunity, improve general condition and quality of life of NSCLC patients without obvious side effects.