Intracholedochal passage pressures (ICPP) were measured during halothane, enflurane and isoflurane anaesthesia as well as during anaesthesia without any volatile agent and in patients with a postoperative T-tube. There were no statistically significant differences in the mean ICPP between the study groups (altogether 49 patients). After i.v. fentanyl 0.1 mg a similar pressure increase (mean 0.5 kPa) was recorded in all anaesthetized groups as compared to a threefold increase (mean 1.6 kPa) in the postoperative group (p less than 0.001) with maximum at about 7 min in all groups. Intraoperative fentanyl did not cause surgically adverse effects i.e. false obstruction due to spasm in the operative cholangiography. It is concluded that all inhalation anaesthetics attenuate the ICPP response to fentanyl.