The agent responsible of more than 80% of the parenterally transmitted non-A-non-B hepatitis, designated hepatitis C virus (HCV), was identified in 1988 thanks to the isolation of the first cDNA reactive clone which was derived from experimentally infected chimpanzees RNA. The recombinant protein expressed from this clone located in the NS4 region of the HCV, allowed to establish the whole HCV-RNA sequence and to develop the first generation enzyme-linked immunoassays for detecting anti-HCV antibodies. Subsequently, other recombinant viral antigens derived from other HCV genome regions, were produced and used to develop second generation screening and confirmatory assays (1991). At least, thanks to a better presentation of the epitopes, since 1993 the performance of third generation reagents have been improved. Nevertheless, in spite of those modifications, the performance of both screening and confirmatory assays still needs to be improved. Moreover, in cases of difficulties of HCV infection diagnosis with serological tests, HCV-RNA detection with genomic amplification tools represents a useful alternative.