We investigated Lewis(a) and Lewis(b) expression of bile ducts in 68 specimens from various kinds of liver disease. In addition, the number of IgM and IgG synthesizing plasma cells in the hepatic inflammatory reactions were immunostained and counted. We found a statistically significant decrease in the number of bile ducts in PBC (primary biliary cirrhosis) in comparison with either chronic active or persistent hepatitis (CAH/CPH). Bile ducts could be detected easily and constantly by their Lewis antigen expression. Isolated bile duct epithelial cells not apparent in H&E sections could be identified by Lewis(a) and b immunostaining. The number of plasma cells in PBC was significantly different than in (CAH/CPH). A large number of IgM plasma cells was a characteristic feature of PBC. However, neither counting of Lewis(a) and b positive bile ducts nor counting of IgM plasma cells was of definite diagnostic significance in the individual clinical case, since no cut-off value could be determined above or below which a PBC was ruled out or proven.