:Objective This studyaimed to detect serum autoantibodies of patients with chronic hepatitis C, and to explorethe significance of autoimmunity in HCV infection. Methods We detected the autoantibodies,including ANA, anti-AMA, anti-Ro-52, of chronic hepatitis C patients ( n = 226) andchronic hepatitis B patients (n = 137 )retrospectively, and explored the relationshipbetween the variation of autoantibodies and the HCV-RNA levels, biochemistry markers, age,gender, responses after interferon treatment. Results 34. 5% ( 78/226 ) and 7.3% ( 10/137) were respectively autoantibodies positive in patients with chronic hepatitis C and inpatients with chronic hepatitis B (χ2 = 34. 396, P < 0.05 ), and 30. 5% (69/226) of cases were ANA positive,otherwise,anti-ANA and anti-Ro-52 also weie detected. The isolating rate of autoantibodieswas 40.7% in 150 patients with positive HCV-RNA ,comparatively, that rate was only 22. 4%in 76 negative HCV-RNA cases. The difference between the two groups was statisticallysignificant(χ2 = 7.473, P<0.05); The levels of ALT,AST, TBIL of negative autoantibodies cases and positive cases were (65.1±24.4 ) U/L,(47.4 ± 22.7 ) U/L, ( 17. 2 ± 8. 2 ) μmol/L and (132.2 ± 49.3 )U/L, ( 100.7 ± 35.2 ) U/L, ( 35.5 ± 14.7 ) μ mol/L, respectively. The difference between the two groups is statisticallysignificant ( t value was 16.012,14. 843 and 9. 000 respectively, overall P < 0. 05 ); The isolating rate of autoantibodies in patients withhepatitis C was related with age, and not related with gender; the response rate ofinterferon treatment was 73.9% in patients with positive autoantibodies, and was higherthan 54. 2% in patients without autoantibodies,but the difference was not statisticallysignificant(χ2 = 0. 975, P >0.05). Conclusions HCV infection can induce autoimmunereaction to produce sevaral autoantibodies,especially in cases with positive HCV-RNA. Theisolating rate of autoantibodies is highly related with age, it can be used for thediagnosis and treatment of hepatitis C to detect autoantibodies. Key words: Hepatitis C; Autoantibodies; Autoimmunity