OBJECTIVE Cell adhesion molecules play an important role in the morphogenesis of developing organs. However, little is known about their expression during intrahepatic bile duct development. METHODS We immunohistochemically investigated the expression of E-cadherin (E-Cad), alpha-catenin (A-Cat) and beta-catenin (B-Cat) during human intrahepatic bile duct development, using 31 fetal livers of various gestational ages. The developmental stages of bile ducts were classified into the ductal plate, migrating biliary cells (remodeling stage), and immature bile ducts (remodeled stage). RESULTS E-Cad was broadly and strongly expressed in the ductal plate with a cytoplasmic pattern, heterogeneously and weakly expressed in the migrating biliary cells with a cytoplasmic pattern, and broadly and strongly expressed in immature bile ducts with a membranous pattern. A-Cat was broadly and strongly expressed in the ductal plate with a membrane pattern, broadly and moderately expressed in the migrating biliary cells with a membranous pattern, and broadly and strongly expressed in immature bile ducts with a membranous pattern. In contrast, expression of B-Cat was weak or slight in the ductal plate, but B-Cat was expressed broadly and strongly with a membranous pattern in migrating biliary cells and in immature bile ducts. Immature hepatocytes rarely expressed E-Cad and A-Cat, but expressed B-Cat with a membranous pattern throughout development. CONCLUSIONS These results suggest that E-Cad, A-Cat and B-Cat are involved in the normal developmental morphogenesis of human intrahepatic bile ducts.