Pegylated-interferon(PEG-IFN)/interferon monotherapy for patients with chronic hepatitis C has been used for two clinical aims; one is for the elimination of hepatitis C virus (HCV), and the other is for the inhibition of hepatocarcinogenesis. In patients with a rapid viral response to PEG-IFN, PEG-IFN monotherapy can efficiently eradicate HCV with decreased side effects. A low dose treatment of interferon is suggested to inhibit hepatocarcinogenesis in patients whose ALT or alpha-fetoprotein (AFP) was reduced in response to the treatment, although the benefits and adverse events of IFN therapy have to be carefully evaluated.