Both high and low anti-hepatitis C virus antibody (anti-HCV) prevalence has been reported in autoimmune chronic active hepatitis. Therefore, we studied 15 consecutive HBsAg-negative, ELISA anti-HCV-positive, autoantibody-positive patients with biopsy proven chronic active hepatitis in order to confirm ELISA specificity by immunoblot test (RIBA-HCV), and to evaluate HCV replication by serum HCV-RNA. Nine patients were anti-nuclear, three type 1 anti-liver-kidney microsomal and three anti-smooth muscle antibody positive. None had associated autoimmune disease. All cases showed mild clinical disease and only moderate necroinflammatory activity. Response to prednisone was poor. RIBA-HCV confirmed ELISA results in all patients. HCV-RNA was found in the serum from 10 patients. Institution of alpha-interferon treatment in three steroid non-responsive patients was followed by prompt normalization of transaminases. Thus, a subgroup of autoantibody-positive chronic active hepatitis can be recognized as HCV-related and should be clinically and etiologically distinguished from autoimmune chronic active hepatitis. Trials of alpha-interferon treatment are worthwhile in this condition.