Objective To study the expression of Th1 and Th2 types cytokines in patients with esophageal squamous cell carcinoma and the clinical significance. Methods The expressions of Th1 ( INF-γ、IL-2) and Th2 (IL-4) types cytokines in cultured peripheral blood mononuclear cells (PBMC) from 30 healthy controls and 45 esophageal squamous cell carcinoma patients were determined by Enzyme-linked immunosorbent assay (ELISA). Results Compared with the control group, the expressions of Th1 type cytokines, IL-2 and INF-γwere significantly lower in the cultured PBMCs from the cancer patients (tINF-γ= 18. 24 ,tIL-2 = 15.31 ,Ps ＜0. 01 ) ,while the expression of Th2 type cytokines,IL-4 was significantly higher in the cultured PBMCs from the cancer patients ( tIL-4 = 5.79, P ＜ 0. 05 ). The expression changes of the cytokines showed a correlation with TNM (tumou-node-metastasis) stage of the tumor. Conclusion The Th1/Th2 shift existed in patients with esophageal squamous cell carcinoma and it might be one of the underline mechanisms of tumor immune escape.