The intracholedochal pressure changes induced by timepidium bromide were studied in 12 patients who had undergone surgery because of gall bladder stones and were receiving transient external bile drainage by the Kehr method. Cholangiomanometric examination, carried out under basal conditions and after an intravenous dose of 15 mg timepidium bromide, revealed a statistically significant decrease in mean intracholedochal pressure in all 12 patients. It is concluded that timepidium bromide is likely to exert a direct action on the sphincter of Oddi, decreasing its basal tone and thus causing a decrease in intracholedochal pressure.