Four liver transplant recipients with recurrent cholangiocarcinoma (CCA) within the allograft biliary tree are described. One patient received a transplant for known CCA and three received transplants for end-stage primary sclerosing cholangitis, in which CCA was found within the hepatectomy specimen. All four developed biliary obstruction due to malignant stricture at the bile duct anastomosis 9-15 months after transplantation. Diagnosis of recurrent CCA was made by means of transhepatic brush biopsy in two patients. Recognition that the biliary tract, especially the anastomosis, is a site of recurrence of CCA should facilitate prompt diagnosis by means of transhepatic brush biopsy in patients with biliary obstruction due to stricture. In addition, because of an association between CCA and primary sclerosing cholangitis, preoperative bile duct biopsy should be considered for liver transplantation candidates with the latter condition. Positive biopsy findings may preclude transplantation.