The sustained antibody response to nuclear envelope gp210 antigen indicates a group of primary biliary cirrhosis (PBC) patients at high risk for the progression to end-stage hepatic failure. To address this issue, we immunohistochemically studied the expression of gp210 antigen in needle liver biopsy specimens from PBC patients using a monoclonal antibody specific for gp210 antigen. The specimens from autoimmune hepatitis (AIH), chronic viral hepatitis B (CHB) and C (CHC) patients served as disease controls. The expression of gp210 antigen was apparently increased on the nuclear envelope of biliary epithelial cells (BECs) of small bile ducts in almost all specimens from PBC. In contrast, the expression of gp210 antigen was negative in BECs of small bile ducts in normal liver, while relatively weak anti-gp210 immunostaining was observed in AIH, CHC and CHB. In addition, the degree of gp210 expression in BECs of small bile ducts was positively correlated to that of portal inflammation, interface hepatitis and lobular inflammation in PBC. These results indicate that the increased expression of gp210 in small bile ducts, which is probably associated with damage to BECs by inflammation, is possibly involved in autoimmune response to gp210 leading to the progression to end-stage hepatic failure in PBC.