The aim of the study was to investigate whether the immunoblot pattern for HCV is a predictor of the response to interferon treatment. In a group of 60 patients with persistent rise of aminotransferase, all were treated with 3-6MU of Alfa-IFN from normal leucocytes every other day for 6 months, followed by one weekly dose of 1-3 MU for 3 months. HCV serum markers were detected before treatment and every three months thereafter. In 22 out of 60 (36.6%) patients aminotransferase normalized and remained so for 3 months after therapy; 12 patients (54.5%) relapsed during a follow-up of 9-12 months. The most frequent pattern in responders and non responders was the positivity to four antibodies (55%). The pattern did not change during or after IFN therapy, nor was it related to the variation of aminotransferases. Three patients lost antibodies linked to viral replication (c100-3, 5-1-1) and 3 others became positive to the same antigens. No changes were observed during the follow-up of patients who had an initial normalization of ALT/AST levels and who then relapsed (either during the maintenance dose or during the whole follow-up:n = 19 pts). Therefore neither the antibody clearance of viral replication (c100-3 and 5-1-1) nor the antibody pattern is a valid predictor as to the efficacy of interferon therapy.