Contraindications to the use of alpha interferon, either in the form of specific contraindications to its use (depression, psychiatric illness, neurological impairment, severe thrombocytopenia, autoimmune disease), or the history of severe side effects or intolerance during a previous course of alpha interferon, or lack of a sustained virological (sustained lost of HCV RNA from serum for more than six months after stopping treatment) response to an adequate course (6 months) of the combination of alpha interferon and ribavirin or (after September 1, 2003) the combination of peginterferon and ribavirin.