The objectives of retreatment with interferon (IFN) in chronic hepatitis C (CH-C) patients are sustained response and a reduction in the risk of hepatocellular carcinoma (HCC). However, it is still unclear, as to which patients are candidates for retreatment with IFN. Eighteen transient responders (TRs) and 15 non-responders (NRs) to IFN therapy in CH-C received retreatment with IFNalpha. Of the 18 TRs, five showed sustained disappearance of hepatitis C virus, two showed sustained biochemical response, 10 continued as TR and one was a NR. Of the 15 NRs, six showed a TR while nine continued as NRs. Responsive cases, which included the virologically or biochemically sustained and transient responders, received either a dose of IFN 1.3 times greater or were treated for a period of 1.3 times longer in the retreatment than the original treatment. We submit that IFN treatment consisting of either a time period or a dosage 1.3 times those of the original IFN administration may be beneficial in the case of TR and NR in chronic hepatitis C patients.