Much has been learned in the past few years concerning the morphology and function of the intrahepatic biliary epithelium. Immunohistochemistry, together with ultrastructural studies has allowed a better identification or the smallest branches of the biliary tree and of subcellular components (cytoskeleton, specializations of the cell membrane, specific receptors). Modulation of the biliary epithelium in response to physiological or pathological stimuli has renewed the interest concerning the existence of facultative stem cells in the liver. More information is needed however concerning the mechanisms of cell loss in vanishing bile duct syndromes.