Biliary obstruction in liver transplants is most commonly due to stricture at the biliary anastomosis. The native common bile duct typically is normal. We retrospectively studied 28 patients with choledochocholedochostomy anastomoses who had marked native and donor extrahepatic bile duct dilatation associated with clinical evidence of biliary obstruction. Operative cholangiograms were compared with postoperative cholangiograms obtained a mean of 50 weeks (range, 2-246 weeks) later. Mean caliber of the native common bile duct increased from 7.5 +/- 2.0 mm on operative cholangiograms to 14.8 +/- 3.9 mm on postoperative cholangiograms (p less than .001). Mean caliber of the donor common hepatic duct increased from 5.9 +/- 1.3 mm on operative cholangiograms to 12.8 +/- 3.8 mm on postoperative cholangiograms (p less than .001). Dilatation of the cystic duct remnant was seen in 15 patients. All patients had surgical revision to choledochojejunostomy with improved results of liver function studies in most cases. Diffuse dilatation of native and donor extrahepatic bile ducts may develop in liver transplant recipients. Typical features include native and donor extrahepatic ducts greater than 12 mm in diameter and a dilated cystic duct remnant on postoperative cholangiography in a patient with otherwise unexplained hepatic dysfunction.