In order to clarify the differences in past history, nutritional condition and, consumption of alcohol and tobacco, and liver dysfunction between the thorotrast patients who developed primary liver cancer and those who did not, 103 persons who had no primary liver cancer in January 1980 were studied. All subjects were military men who had undergone angiography with thorotrast between 1943 and 1946. Twenty persons developed hepatocellular carcinoma and 16 developed intrahepatic bile duct carcinoma by April 1987, whereas 67 are still alive without any cancer. There was no difference in age or period after thorotrast infusion between those two groups of patients in January 1980. A difference in history of hepatitis and/or jaundice and presence of hepatic dysfunction was found between the subjects who developed primary liver cancers and those who did not. These findings suggest that an anamnestic history of hepatitis and liver dysfunction are risks for development of thorotrast-induced liver cancer. On the basis of the above findings, early detection of liver dysfunction offers a possibility of early diagnosis of primary liver cancer.