Renal function and other factors that possibly affect the outcome of operation were measured in 24 patients with obstructive jaundice and in 15 non-jaundiced controls. The preoperative features that were associated with a poor postoperative recovery from obstructive jaundice were a raised serum fibrinogen/fibrin degradation product concentration, infection, hypoalbuminaemia and a low glomerular filtration rate. Preoperative serum fibrinogen/fibrin degradation product concentrations were raised in 4 of the 6 jaundiced patients who died after surgery but in none of the controls, in whom there was no mortality. In the jaundiced patients there was a greater incidence of postoperative renal impairment than in the controls. All patients were given mannitol during operation. Further mannitol was required after surgery in 13 of the 24 jaundiced patients in order to maintain urine flow rate despite adequate intravenous fluids being given. In contrast, only 1 of the 15 control patients required post operative mannitol. It is emphasized that repeated doses of mannitol can lead to a profound natriuresis and adequate intravenous saline should be given.