Sera from 209 dialysis patients were tested for antibodies to hepatitis C virus (anti-HCV) by a 2nd generation enzyme-linked immunoassay (ELISA 2) using nonstructural and core antigens. Confirmation of reactivity was obtained by a 2nd generation immunoblot assay (RIBA 2) for antibodies to 4 separate antigens (5-1-1, c100-3, c33c, c22-3). ELISA 2 was positive in 99 sera, 95 of which were confirmed by RIBA 2, thus accounting for an anti-HCV prevalence of 45.5%. Anti-HCV positivity was correlated to longer duration of dialysis therapy (p < 0.001), higher number of transfusions (p < 0.001), history of kidney transplant (p < 0.001) and of serum alanine/aspartate aminotransferase (AST/ALT; p < 0.001) or γ-glutamyltransferase (GGT) (p < 0.001) increments. The most frequent RIBA 2 patterns were: reactivity to all 4 antigens (34 patients) and to c33c and c22-3 (45 patients). The former patients, compared to the latter, had higher values of AST (p < 0.08), ALT (p < 0.02), GGT (p < 0.005), IgG (p < 0.05). It is possible that the reactivity to all 4 antigens of RIBA 2 is a clue of a greater activity of viral hepatic disease