Psychiatric disorders or drug addiction are often regarded as contraindications against the use of Interferon-alpha in patients with chronic hepatitis C. The investigators aim is/was to get prospective data about adherence, efficacy and mental side effects of IFN-alpha treatment in different psychiatric risk groups compared to controls. In a prospective trial, 81 patients with chronic hepatitis C (positive HCV-RNA and elevated ALT) and psychiatric disorders (n=16), methadone substitution (n=21), former drug addiction (n=21) or controls without psychiatric history or addiction (n=23) should be/were treated with a combination of IFN-alpha-2a 3 x 3 Mio U/week and ribavirin (1000-1200 mg/day).