There are approximately 1 million Hepatitis C (HCV) patients in the US who have failed to respond to, or cannot tolerate, interferon or interferon plus ribavirin therapy. Significant adverse effects of interferon therapy include bone marrow depression (with reduced white blood cell and platelet counts) and major psychiatric disorders (especially depression). Ribavirin is associated with hemolytic anemia in a minority of patients who are treated with it. Patients with chronic HCV infection have a very low incidence of spontaneous viral clearance, have progressive disease, and have a continuing medical need for more efficacious and safer therapy. There is a significant unmet medical need for therapy in HCV patients who cannot (or will not) tolerate interferon-based treatment.