Among anti-HCV antibody tests, we compared one first generation kit(Ortho Co.) and two second generation kits(Eiken Kagaku-sya, Abbott Co.). Discrepancies between results from the tests of the three kits were examined by conducting confirmatory tests including polymerase chain reaction and reviewing clinical data. Among 240 subjects including patients with chronic liver disease, 67.9% were negative to all the three kits, 19.2% were positive to all, and 12.9% showed discrepancies between results from the three kits. The discrepancy is caused not only by non-specific reactions previously known in first generation kits but also by the kinds of epitope and their combinations in second generation kits.