BACKGROUND: Recent studies suggest a potential impact of Th17 cells on tumor. In the present study, we investigated the distribution of Th17 cells in relation to Foxp3-expressing T cells in the tumor-infiltrating lymphocytes (TILs) from patients with uterine cervical cancer (UCC), cervical tissues from patients with cervical intraepithelial neoplasia (CIN) and healthy cervical tissues. METHODS: Th17 cells and Foxp3-expressing T cells were evaluated by immunohistochemical staining. IL-6, TGF-β, IL-17 and IL-10 were detected by enzyme-linked immunosorbent assay (ELISA). Immunohistochemical staining for microvessel density (MVD) was performed in order to assess the association of IL-17 expression with angiogenesis. RESULTS: Compared with controls, patients with UCC or CIN had a higher proportion of Th17 cells and Foxp3-expressing T cells, when the ratio of Th17/Foxp3-expressing T cells in TILs was decreased in individual cases, it was more markedly decreased in TILs than normal cervical tissues. Meanwhile, the cytokine(IL-6, TGF-β and IL-10) concentrations were significantly higher in UCC patients than those in healthy controls. Interestingly, the levels of intratumoral Th17 cells were positively correlated with MVD in tumors. CONCLUSIONS: The imbalance of Th17/Foxp3-expressing T cells may play critical roles in the development and progression of UCC and Th17 cells may promote tumor progression by fostering angiogenesis.