Abstract: Objective To study the role of HCV core antigen(HCV-cAg) in diagnosis and treatment of HCV infection. Methods Total HCV core antigen and HCV-Ab were detected by ELIA and third generation ELIA,respectively.Plasma HCV-RNA level and liver function were tested by ultraviolet ray assay.Nucleic acid was quantified by RT-PCR. Results The HCV-cAg was detected in 38 out of the 90 patients(42.22%).The HCV-RNA was significantly higher in HCV-cAg positive patients than in HCV-cAg negative patients100%(38/38) vs 71.15%(37/52),P<0.05.The ALT was significantly higher in ALT positive patients than in ALT negative patients63.16%(24/38) vs 40.38%(21/52),P<0.05.The ALT was significantly higher in HCV-cAg negative patients than in HCV-cAg positive patients59.62%(31/52) vs 36.84%(14/38),P<0.05.HCV-cAg was correlated with HCV-RNA and ALT in chronic hepatitis C patients and could reflect the damage of liver function. Conclusion HCV-cAg is a reliable marker of chronic HCV infection.