Statistical analyses have been made by the Liver Cancer Study Group of Japan of 4031 cases of primary liver cancers diagnosed at 155 institutes during the period of Jan. 1, 1968-Dec. 31, 1977, based on the questionnaire in the form of individual file. They comprised 2411 cases of hepatocellular carcinoma, 268 of cholangiocellular carcinoma, 58 of the mixed type, 69 of hepatoblastoma, 23 of others, and 1202 cases with only clinical diagnosis. The survey and analyses mostly based on the histology-proven cases included gross anatomical and histological features of tumors, grades of anaplasia and growth patterns of tumor cells, pathology of noncancerous liver portion, frequency of accompanying cirrhosis or fibrosis, distant metastases, past history, frequency of hepatitis in the past history, frequency of positive HBsAg and anti-HBs, familial clustering of positive HBsAg tests, age distribution, subjective symptoms, objective signs, serum alpha-fetoprotein, celiac angiography findings, number of operations performed, kinds of surgical approaches made, extents of hepatic resection, prognosis in terms of survival in relation to various surgical treatments, chemotherapeutic agents used and routes of administration, prognosis as related to the accompanying parenchymal liver disease, and overall survival.