Recently the formation of bile acid glucosides has been described as a novel conjugation mechanism in vitro and in vivo. In 10 patients with extrahepatic cholestasis caused by carcinoma of the head of the pancreas we investigated excretion rates and profiles of urinary bile acid glucosides. Urinary bile acid glucosides and, for comparison, bile acid glucuronides were extracted and characterized according to established methods. In controls total urinary bile acid glucoside excretion was 0.22 ± 0.03 μmol/24 hr (mean ± S.E.M.)–in the range of bile acid glucuronide excretion (0.41 ± 0.06 μmol/24 hr; mean ± S.E.M.). A gas chromatography–mass spectrometry–characterized trihydroxy bile acid glucoside of stillunknown hydroxyl positions accounted for 65% of total urinary bile acid glucosides. In extrahepatic cholestasis total urinary bile acid glucoside excretion was 0.52 ± 0.13 μmol/24 hr (mean ± SEM), yet significantly lower than bile acid glucuronide excretion (1.53 ± 0.13 μmol/24 hr; mean ± SEM; p EPATOLOGY 1991;13:656–662.)