The sera of 132 patients with liver diseases were examined for antibody to consituents of ribosomes by the bentonite ribosomes flocculation test. The ribosome antibody was detected in 11 of 35 cases (3%) of acute hepatitis, in 7 of 41 cases (17%) of chronic hepatitis, in 3 of 39 cases (8%) of liver cirrhosis. The ribosome antibody was absent detected in the 36 patients with primary biliary cirrhosis, liver carcinoma, obstructive jaundice and toxic hepatitis or in the 20 normal donors. The ribosome antibody seemed to be present only in sera of patients with chronic active hepatitis.