The Liver Cancer Study Group of Japan analyzed statistically 12,887 cases of primary liver cancer diagnosed from January 1, 1982 to December 31, 1985 in more than 500 institutes throughout the country. The study was based on the answers to 258 questions. There were 4354 cases of hepatocellular carcinoma, 256 cases of cholangiocellular carcinoma, 49 cases of mixed carcinoma, 22 cases of hepatoblastoma, 10 cases of sarcoma, and 74 other cases. The survey and analysis, based mainly on 4765 histologically proved cases, included gross anatomic and histologic features of the tumors, pathology of the noncancerous portion, distant metastases, past medical history, frequency of positive Hepatitis B surface antigen and Hepatitis B surface antibody, age distribution, various diagnostic procedures, surgical procedures, and survival rate in relation to operative curability and tumor stage.