Liver tissues of 223 autopsy cases of cirrhosis and hepatocellular carcinoma were examined for liver cell dysplasia in relation to hepatitis B surface antigen (HBsAg) detected with orcein stain. Liver cell dysplasia was found in 94 cases (42.2%): 37 were from cases of cirrhosis only, and 53 were from cases of cirrhosis with hepatocellular carcinoma. There was a significant difference in the overall incidence of HBsAg in cases with and without dysplasia (70.2%:32.6%). A similar difference was found in all groups, i.e., those with cirrhosis, cirrhosis with hepatocellular carcinoma, and hepatocellular carcinoma only, in which none of 11 cases of HBsAg negative had dysplasia. A good correlation was seen between the semiquantitative grade of dysplasia and the incidence of HBsAg. These findings suggest a close relationship of HBsAg with liver cell dysplasia.