The Chiron RIBA HCV (Hepatitis C Virus) test system is proposed to biological laboratories for detection and confirmation of antibody anti-HCV. The RIBA HCV test is an in vitro qualitative immuno-assay based on recombinant HCV antigens (c100-3 and c5-1-1) immobilized on nitrocellulose strips. This study was performed on 764 blood donors reactive by Elisa Ortho anti-HCV and selected upon the Elisa ratio (1/3 of sera with low ratio 1-2, medium 2-4 and high greater than 4). The results show that 32% of samples are reactive (242/765), 42% (319/764) are non reactive and 26% (203/764) are indeterminate. The RIBA results according of the Elisa ratios and the ALT levels show that 65% of seras with ratios greater than 4 and 83% of seras with ALT greater than 2 N are reactive. None of 60 samples with ratios greater than 4 and ALT greater than 2 is negative.