Abstract: Objective To study the expressions of Th1 and Th2 type cytokines in patients with esophageal squamous cell carcinoma and the influence of operation on such expressions.Methods Enzyme-linked immunosorbent assay (ELISA) was used to detect Th1 (IL-2 and INF-γ) and Th2 type cytokines (IL-4, IL-6 and IL-10) in cultured peripheral blood mononuclear cells (PBMCs, for 48 h) from 30 healthy controls and 46 esophageal squamous cell carcinoma patients (collected before and 8 and 30 d after operation, respectively).Results Compared with the control group, the expressions of Th1 type cytokines, IL-2 and INF-γ, were significantly depressed in the PBMCs of the cancer patients (P<0.05), while expression of Th2 type cytokines, IL-6 was significantly enhanced (P<0.05), and IL-4 and IL-10 showed only slight enhancement. Such changes in the expressions of the cytokines showed a correlation with TNM (tumor-node-metastasis)stage of the tumors. After operation, the expressions of Th1 type cytokines increased and Th2 type cytokines decreased.Conclusion s Th1 cells are suppressed in patients with esophageal squamous cell carcinoma, while the function of Th2 cells is enhanced. Operation may reverse such changes, and dynamic detection of Th1 and Th2 type cytokines may indicate the prognosis, therapeutic effect and risks of relapse and metastasis.