Background Interleukin-17 (IL-17),which exerts strong pro-inflammatory effects,has emerged as an important mediator in inflammation-associated cancer.The aim of this study was to clarify the relationship between IL-17 and tumor associated macrophages (TAMs),and the correlation of the microvessel density in the development of laryngeal squamous cell carcinoma (LSCC).Methods Histopathological observations and immunohistochemistry staining for IL-17,CD68,and CD34 were performed on 72 specimens (32 cases of LSCC,20 cases of adjacent tissues of carcinoma as controls,and 20 cases of chronic hypertrophic laryngitis).Double immunohistochemical staining was done to determine which cells expressed IL-17.Real-time quantitative PCR determined the mRNA expression of IL-17.ELISA was used to detect the expression of the serum level of IL-17 in the three groups.Results The inflammation response had increased in LSCC.Overexpression of IL-17 and CD68 protein were seen in LSCC (P ＜0.01).The expression of IL-17 was different between well and poorly differentiated LSCC (P ＜0.01).The IL-17expressing cells were mainly located in macrophages (CD68+/IL17+) as demonstrated by double immunohistochemical staining.IL-17 expression significantly correlated with high microvessel density (CD34+) in LSCC (P ＜0.05).Relatively higher mRNA expression levels of IL-17 were seen in LSCC compared to the controls (P ＜0.05).The serum expression of IL-17 was similar among the three groups (P ＞0.05).Conclusion IL-17 was expressed by TAMs,and IL-17 may significantly correlate to the differentiation and angiogenesis in the development of LSCC.