In Hungary over the past 5 years more than thousand patients with chronic viral hepatitis have been examined and included in a treatment program with interferon (IFN) at 16 major hepatology centers, using unified diagnostic and therapeutical criteria. Authors give an account of their experiences on the clinical features of patients with chronic viral hepatitis and report the results of the treatment with IFN. According to the rules and availability of IFN for patients with chronic viral hepatitis in the country, virtually the entire Hungarian population with this diseases who required IFN therapy have been included. A total of 94 patients suffered from hepatitis B virus (HBV) infection, in addition 11 HBV + hepatitis Delta virus (HDV), 24 HBV + Hepatitis C virus (HCV) related liver disease, and 993 had chronic hepatitis C. IFN therapy for chronic HBV hepatitis consisted of IFN 5 MU thrice weekly for 6 months, and resulted in 33% seroconversion and sustained remission with 14% HBsAg clearance. For chronic hepatitis C treatment protocols (dose of IFN and duration of therapy) have changed with the time (from a weekly dose of 3 x 3 MU IFN for 6 months, to 3 x 3 MU for 12 months), and even a combination with ribavirin has been introduced. Although the therapeutic results showed a gradual improvement form a 13% sustained response over 22% in the first and second periods, respectively, differences were most significant with the advent of the combination therapy, that resulted in 36% remission rate. Only fibrosis in histology and baseline pretreatment HCV-RNA level appeared as predictors of response in chronic hepatitis C. Neither age nor gender did influence the outcome, but longer duration of treatment and higher total dose of IFN resulted moderately higher sustained remission rates. The experiences are in accordance with findings of suboptimal efficacy of IFN monotherapy reported worldwide and emphasize the need of seeking for newer and combination therapeutic modalities for these chronic viral diseases.