Hepatitis C virus (HCV), identified in 1989, is the main agent of Non-A, Non-B hepatitis. The number of HCV carriers in France is estimated between 500,000 and 2 millions. The main risk factors for HCV infection are blood products transfusion and i.v. drug abuse. Cirrhosis occurs in 30% of cases with a delay ranging from 10 to 30 years, and hepatocellular carcinoma in 2.5% of cases. Interferon is, for instance, the only effective therapy in patients with chronic hepatitis C; however, prolonged response (in terms of transaminase normalization) after stopping treatment occurs only in 20% of patients.