The effect of secretin on bile flow, biliary clearance of 14C-erythritol and bile composition was studied in fasting, chloralose anesthetized cats. Secretin (2 U.kg-1 . h-1) increased from values below the values above the erythritol clearance, which did not change significantly. It is therefore concluded that secretin altered ductular transfer of fluid from a net reabsorption to a net secretion of a bicarbonate rich fluid. Secretin did not affect the sphlanchno-hepatic hemodynamics or the overall function of the liver and Indomethacin did not significantly alter the response to secretin.