A new radiopharmaceutical for hepatobiliary scanning, 99Tcm Iodida, which has significant advantages in patients with high bilirubinaemia, was used to assess biliary tract complications in 30 consecutive liver transplant patients. There was adequate hepatic extraction and excretion for diagnostic imaging even in patients with serum bilirubin levels up to 877 mumol l-1 (51.6 mg dl-1). Twelve out of 12 cases (100%) without any biliary complication were correctly diagnosed. Extrahepatic obstruction was recognized in 5 out of 7 cases (71%). In one case the scintigraphic findings showed no perfusion of the transplanted liver caused by vascular thrombosis due to acute rejection. One small biliary leak was missed. The correct diagnosis of intrahepatic cholestasis was made in 3 out of 9 patients. However six equivocal studies were observed in profoundly jaundiced patients with bilirubin levels above 400 mumol l-1 due to difficulties in differentiating extrahepatic obstruction from severe intrahepatic cholestasis. Quantitative analysis of the kinetics of 99Tcm Iodida may permit better discrimination between the wide variety of disease in the posttransplant period.