In the 15th Nationwide follow-up survey of primary liver cancer, 18,843 newly registered patients (1998-1999) and 18,405 follow-up patients from 791 hospitals in Japan were analyzed. Of the newly registered patients, approximately 95% were patients with hepatocellular carcinoma (HCC) and 3.3% had intrahepatic cholangiocarcinoma (ICC). The patients were assessed using 194 items that were related to epidemiological and clinicopathological factors, diagnosis, and treatment. Furthermore, the survival rates of all of the newly registered patients in the 10th-15th follow-up survey were calculated for each histological type, background factor(s) and treatment, respectively. In patients with hepatocellular carcinoma, the survival rates of patients who underwent hepatectomy, ethanol injection therapy, microwave coagulation therapy, or transcatheter arterial embolization were calculated by tumor size, tumor number, and clinical stage. This follow-up survey will be helpful to assess the progress of research and medical practice in the treatment of primary liver cancer.