Objective To investigate relationships between signal/cutoff (S/CO) ratios of antiHCV recombinant immunoblot assay (RIBA) and their positivity with different chemiluminescence immunoassay(CLIA) reagents.Methods A case-control study was performed.From March 2014 to March 2015,anti-HCV antibody was detected in 2 616 serum of outpatients and inpatients coming from Department of Clinical Laboratory,Qilu Hospital of Shandong University by three kinds of homemade CLIA reagents and one imported CLIA reagents.The positive samples were further tested by RIBA.The correlation between the positivity and the S/CO ratios was analyzed.The difference between different reagents were compared by x2 method.Results The predicted positivities of Shandong Laibo were 97.8％ and 33.3％ with S/CO ratio ≥ 26.8 and 1 to 26.8,respectively;The predicted positivities of Beijing Yuande were 96.7％ and 20％ with S/CO ratio ≥ 16.6 and 1 to 16.6,respectively;The predicted positivities of Beijing Kemei were 97.0％ and 9.8％ with S/CO ratio ≥ 16.7 and 1 to16.7,respectively;The predicted positivities of Abbott were 96.9％ and 12.8％ with S/CO ratio≥5 and 1 to 5,respectively.Conclusions Anti-HCV CLIA S/CO ratio and RIBA confirmatory test results have some relevance.Domestic reagents also can refer to import reagents determine the relationship between the positivity and the S/CO ratio.Different domestic reagent of positivity has different S/CO ratio.Although each reagent S/CO ratio to the same positivity has large difference,suggesting each manufacturer should set their products corresponding values according to the situation,providing reference for the clinical use of unit in result determination of the clinical trials.