A number of factors are known to be related to increased mortality of surgery in obstructive jaundice, yet precise identification of patients at greatest risk is difficult. We have studied the elimination of the minor analgesic antipyrine as a dynamic measure of hepatic metabolic function in patients with obstructive jaundice undergoing percutaneous transhepatic biliary drainage. Of 46 patients in whom antipyrine clearance was measured, 21 had an antipyrine half-life less than 15 hours and 2 died in the hospital. Of 25 who had an antipyrine half-life greater than 15 hours, 10 died in the hospital, 4 before undergoing surgery. The difference in mortality is significant (p less than 0.05). Of 15 patients who had serial antipyrine tests, only 4 showed an improvement during percutaneous transhepatic biliary drainage. The antipyrine test may be a useful predictor of outcome in obstructive jaundice, and this study suggests that hepatic function does not improve in all patients undergoing preoperative percutaneous transhepatic biliary drainage.