In 70 patients with hepatocellular carcinoma without history of antineoplastic chemotherapeutic drugs, anabolic and contraceptive steroids, representative sections of nonneoplastic liver tissue were examined for the presence of etiological markers. Hepatitis B surface antigen-positive hepatocytes were found in 16 (22.8%), alpha-1-antitrypsin globules in 3 (4.2%), Mallory bodies in 9 (12.8%), acicular inclusions in 1 (1.4%), diffuse giant mitochondria in 2 (2.8%), copper-binding protein in 25 (35.7%), greater amount of hemosiderin in 9 (12.8%) cases. Thorotrast was not detected. One or more markers were seen in 38 (54.3%) cases, most frequently in association with liver cell dysplasia and alcoholism. The presence of hepatitis B surface antigen in livers with dysplastic foci was highly significant as compared to organs showing no dysplasia. Only the mentioned antigen and the alpha-1-antitrypsin globules were found to indicate the etiology of the underlying liver lesion. The value of the other markers was found inconsistent in etiological diagnosis.