['Maintenance of the cellular integrity of the biliary epithelium may involve the production of mucins and mucin-associated peptides. In the luminal gastrointestinal tract, mucins and the mucin-associated trefoil peptides (TFF) are integral to cytoprotection and cellular repair of the mucosa.', 'Samples of normal and diseased human liver tissue were examined using histological and immunohistochemical techniques, for the expression of TFF and mucins. Bile ducts were classified as small, medium or large depending upon the number of biliary epithelial cells. TFF expression was demonstrated in biliary epithelial cells of both normal and diseased liver tissue. TFF expression was greatest in the large bile ducts. In normal liver tissue, expression of at least one TFF was demonstrated in 2-7% of small bile ducts, 5-31% of medium bile ducts and 31-85% of large bile ducts. Seventy-seven percent of large bile ducts secreted mucins and all three TFF concurrently, compared with 3% of medium bile ducts and no small bile ducts. Biliary disease resulted in an increased expression of TFF1 and TFF3 in the medium bile ducts.'] Is biliary epithelial trefoil peptide expression increased in biliary diseases?