A 57 year old man with auto-immune chronic active hepatitis, regularly treated with immunosuppressive therapy, had hepatocellular carcinoma (HCC) 10 years after diagnosis of the hepatitis. Assays of the hepatitis C virus antibodies against capsid and non-structural proteins revealed seronegativity in serial serum samples of this patient stored in the previous 10 years during follow up. The seronegative hepatitis C antibodies excluded hepatitis C virus as the cause of the HCC. The occurrence of HCC in this case suggests the necessity of surveillance for early detection of liver cancer in patients with auto-immune chronic active hepatitis undergoing long-term immunosuppressive therapy.