Objective To study the role of interleukin-6(IL-6)in the pathogenesis of prostate cancer and its clinical significance. Methods Immunohistochemistry and RT-PCR were used to detect the expression of IL-6 protein and mRNA in frozen prostatic adenocarcinoma,adjacent benign prostatic tissue,and prostate cancer cell lines PC-3 and LNCaP. The serum levels of IL-6 in patients with prostate cancer and healthy controls,and the supernatants of prostate cancer cell cultures were measured by using ELISA. Results The IL-6 protein levels in prostate cancer tissue and PC-3 cells were significantly higher than those in adjacent benign prostatic tissue and LNCaP cells. The serum IL-6 levels in the patients with prostate cancer were markedly higher than those in the healthy controls. The IL-6 levels in supernatants in PC-3 cells were notably higher than those in the LNCaP cells. Conclusion The IL-6 gene may act as an important regulator in prostate cancer progression and may be one of the causes of prostate cancer conversion from an initially androgen-dependent state into an androgen-independent state.