Aim: To explore the role of interleukin-17 (IL-17) in the pathogenesis and progress of chronic hepatitis B virus (HBV) related liver diseases, especially in hepatitis B related liver fibrosis., Methods: Whole vein blood was obtained from the patients with chronic hepatitis B (CHB) (n=36), liver cirrhosis (LC) (n=42) including child-pugh A (n=15), child-pugh B (n=12), child-pugh C (n=15), primary hepatitis carcinoma (PHC) (n=34), chronic severe hepatitis (n=30) and normal control (n=20).The level of serum IL-17 and the expression of IL-17 mRNA in peripheral blood mononuclear cell (PBMC) were analysed by ELISA and RT-PCR respectively. Serum IL-17 and liver fibrosis index (C-IV, LN, HA) concentration of LC classified by child-pugh scores were detected by ELISA., Results: The level of serum IL-17 and the expression of IL-17 mRNA in PBMC in four HBV infectious groups were higher than that in control group ( P<0.01). The level of serum IL-17 and the expression of IL-17 mRNA in PBMC in LC group was higher than that in other groups ( P<0.01). The level of serum IL-17 and liver fibrosis index in child-pugh C group in LC patients were higher than that in Child-pugh B group and that in child-pugh B group were higher than that in child-pugh A group (P<0.01). The level of serum IL-17 in LC group positively correlated to child-pugh score and liver fibrosis index (C-IV, LN, HA) (r=0.582, 0.568, 0.682, 0.764, P<0.01)., Conclusion: IL-17 is obviously increased in HBV related liver diseases, especially in hepatitis B related liver cirrhosis, indicating that IL-17 may play a part in the development of HBV related liver diseases, especially the pathophysiology of hepatitis B related liver fibrosis.