Although interleukin (IL) 17A can promote angiogenesis in several tumors, there are limited clinical evidences on cancer about the correlation between serum vascular endothelial growth factor (VEGF) and IL-17F, which is the most homologous to IL-17A. In this study, serum concentration of IL-17F and VEGF from healthy (n = 28), leukoplakia (n = 15), and oral squamous cell carcinoma (OSCC) groups (n = 85) were assessed and showed that IL-17F level was remarkably downregulated from healthy group (394.3 pg/ml) to OSCC group (82.96 pg/ml). Conversely, the OSCC group had a highest level of VEGF (P < 0.05) in whole groups, and there was a negative correlation between IL-17F and VEGF in serum or in the peripheral blood mononuclear cells (PBMCs) at mRNA level. Moreover, the lowest ratio of IL-17F/VEGF was found in OSCC patients (P < 0.05) and lower ratio of IL-17F/VEGF correlated to higher tumor stage and lymph node metastasis. Furthermore, the serum level of IL-17F and the ratio of IL-17F/VEGF were positively associated with the numbers of CD3(+) CD4(+) T cells, which indicated that serum IL-17F could originate from PBMCs during the development of OSCC, and could be used for the diagnosis by effectively distinguishing OSCC patients from healthy individuals.