Of a total of 2342 patients with type-C chronic hepatitis treated with interferon (IFN) at this hospital, 3 patients developed jaundice during the course of IFN therapy, but all 3 of them exhibited negative conversion of hepatitis C virus (HCV)-RNA following readministration of IFN. All 3 patients were assessed as having "probable autoimmune hepatitis (AIH)" in accordance with the AIH scoring system, indicating association with an "autoimmune phenomenon". Readministration of IFN at a low-dose induced activation of the autoimmune phenomenon, leading to fulminant hepatocellular impairment. As a result, HCV-RNA content dropped dramatically, possibly contributing to the negative conversion of HCV-RNA noted following the readministration of IFN. At present, no adequate therapy has been established for type-C chronic hepatitis with autoimmune manifestations. However, in conclusion, our findings suggested that: IFN should be a frontline regiment: (1). if autoantibody titers are low or patients are rated as having "probable AIH" or lower in accordance with the AIH scoring system, indicating a strong link to chronic hepatitis or (2). if IFN is expected to be efficacious on the basis of genotype of HCV-RNA level; even if there is acute exacerbation of type-C chronic hepatitis, IFN should be re-administered in the HCV-RNA level has dropped subsequently.