Morphological changes of interlobular bile ducts in asymptomatic or symptomatic primary biliary cirrhosis (PBC) and chronic hepatitis with ductal lesions were investigated. It was supposed that bile duct lesions found in PBC and chronic hepatitis could be distinguished histologically. There were identical epithelial changes between symptomatic PBC and asymptomatic one, but granulomas were more often found in asymptomatic PBC than in symptomatic PBC. Numbers of interlobular bile ducts per portal tract and the rates of portal tracts without interlobular duct in asymptomatic PBC were intermediate between symptomatic PBC and chronic hepatitis. Serial sections revealed that some bile ducts were able to be followed by ductules in asymptomatic PBC. From these results, numbers of interlobular bile ducts are undoubtedly decreased in asymptomatic PBC but not so much as in symptomatic one. This observation may be attributable partially for taking asymptomatic course.