Primary biliary cirrhosis (PBC) is a chronic liver disease of unknown etiology. Several immunological abnormalities found in PBC support the hypothesis that autoimmune mechanisms are involved in its pathogenesis. The complement system being an important constituent of the immune system had not been extensively studied regarding its relationship with PBC. However, some workers reported abnormally high serum levels of some complement components with the exception of C4 that was found to be low. Here we review the literature and analyze the possible roles played by the complement system in PBC.