The high prevalence of antibodies to hepatitis C virus (HCV) in patients with hepatocellular carcinoma (HCC) in Japan suggests that the virus has a close relationship to hepatocarcinogenesis (1-4). HCV causes chronic inflammation of the human liver and HCC may finally develop, by way of an unknown mechanism. Interferon (IFN), which has an antiviral effect, is widely used for treatment of chronic hepatitis C infection (5). In Japan, about 40% of such patients have been cured of the infection by IFN therapy (6). The most suitable criteria for identification of a complete response to IFN are the most rigorous: both the disappearance of HCV RNA, verified by the polymerase chain reaction (PCR), and alanine aminotransferase activity in the normal range for at least six months after the end of the therapy. In the cured patients, the liver disorder and hepatocarcinogenesis are thought to stop progressing. However, few such patients have been monitored for years following the treatment (7-8). In this article, we describe a patient with small HCC in the caudate lobe after complete response to IFN therapy for chronic hepatitis. We suggest the necessity for regular liver checks for patients from whom HCV is eliminated by IFN therapy.