Interferon (IFN) therapy allows the eradication of hepatitis C virus (HCV) in some part of patients with chronic hepatitis C which is major cause of hepatocellular carcinoma (HCC). To clarify characteristics and prognoses of HCC detected in these patients (sustained responders to IFN), we compared HCC in sustained responders with HCC detected in patients without a sustained response (non-sustained responders). Characteristics and prognoses were compared in nine cases of HCC detected in sustained responders after IFN therapy and 61 cases of HCC detected in non-sustained responders at one of five our institutions. HCC in sustained responders often were larger (P=0.0051), less differentiated tumor (P=0.0084) than HCC in non-sustained responders when it was detected. No differences were observed in overall survival rate between sustained responders and non-sustained responders, but disease-free survival was higher in cases of HCC in sustained responders (P=0.0494). HCC detected in sustained responders often appear more advanced when detected than HCC in non-sustained responders, but recurrence seems to be less frequent when the initial HCC is treated sufficiently.