The prevalence of antibodies against hepatitis C virus (anti-HCV) in an unselected series of 45 mixed cryoglobulinemia patients was assessed by an enzyme linked immunosorbent assay (Chiron ELISA HCV, Second Generation). The anti-HCV specificity was evaluated by a recombinant based immunoblot assay (Chiron RIBA HCV, Second Generation Assay). HBV-related markers and HIVAb were detected in the same samples. The prevalence of anti-HCV observed in mixed cryoglobulinemia was compared with 80 patients with other immunological systemic diseases. Anti-HCV were found in 91% of mixed cryoglobulinemia patients, and confirmed by RIBA in all cases; on the other hand, anti-HCV were practically absent in other control diseases. HBV markers were recorded in 49% of mixed cryoglobulinemia subjects; while HIVAb were constantly absent. These data give us new insights into the etiopathogenesis of mixed cryoglobulinemia.