In almost all patients in whom interferon(IFN) treatment dose not result in persistent negative findings for HCV-RNA, HCV-RNA levels show a rebound after discontinuing the administration. In most patients, HCV-RNA levels after administration are increased compared to pretreatment values. When a rapid increase in HCV-RNA levels causes transient exacerbation of transaminase levels, HCV-RNA levels then rapidly decrease. In two-step interferon rebound therapy(TIRT), IFN is additionally administered when HCV-RNA levels are decreased. We previously reported that TIRT was useful for treating type 1b patients with an HCV-RNA level of 1 Meq/ml or more who did not respond to IFN treatment. In the year 2000, health insurance covered the additional administration of IFN. The use of TIRT for additional administration may further improve treatment response in patients who do not respond to IFN treatment.