Objective To study the relationship between the change of T lymphocyte subsets and NK cells in esophageal cancer patients and radiotherapy effect.Methods The levels of T lymphocyte subsets and NK cells were detected by flow cytometry in 56 cases with histologically confirmed esophageal cancer treated with radiotherapy and contrasted to the healthy people.Results In patients with esophageal cancer,peripheral blood T cells,Th cells,Th / Ts were decreased significantly compared with the control group [(58.3±5.2) ％ vs (65.8±7.2) ％,(28.7±5.0) ％ vs (38.1±7.7) ％,(1.0±0.3) vs (1.6+2.7),all P ＜ 0.05],while the Ts cells were significantly increased [(28.8±5.3) ％ vs (25.4±5.7) ％,P ＜ 0.05].There was no significant difference between peripheral blood T lymphocyte subsets,Th/Ts ratio change and patient age,sex,tumor staging,histological differentiation and pathological lesions.After radiotherapy,the levels of peripheral blood T cells,Th cells,Th/Ts cell ratio and NK cells in esophageal cancer patients were increased [(66.9±4.5) ％ vs (59.4±4.9) ％,(40.6±5.6) ％ vs (29.1±4.2) ％,(1.6+0.5) ％ vs (1.0±0.4) ％,(16.2±3.9) ％ vs (14.6±3.2) ％,all P ＜ 0.05],while the Ts cells decreased [ (25.4±3.6) ％ vs (28.4±5.7) ％,P ＜ 0.05].The increasing degree of peripheral blood T cells,Th cells were closely related to the lesion progress,the difference was significant (both P ＜ 0.05).Conclusion Cellular immune function in patients with esophageal cancer is low.Detection of T lymphocyte subsets,NK cells can be used for immune monitoring of patients with esophageal cancer.