The authors performed percutaneous biliary ductal shave biopsy through an existing transhepatic biliary drainage tract with use of the Simpson atherectomy catheter. The technical feasibility, sensitivity, and complications of this endoluminal biopsy method were studied when used for diagnosis of biliary ductal and pancreatic neoplasm. Nineteen bile duct shave biopsies were performed in 18 patients with symptomatic biliary obstruction by using a 9-F Simpson directional atherectomy catheter. Seven of the 18 patients underwent nine negative percutaneous needle biopsies prior to undergoing percutaneous biliary drainage. Results of previous transcatheter brush biopsies performed through the transhepatic tract were negative in all patients. A histologic diagnosis was obtained in 15 of the 19 procedures (sensitivity, 0.79) and included cholangiocarcinoma (n = 7), pancreatic carcinoma (n = 5), metastatic carcinoma (n = 2), and primary sclerosing cholangitis (n = 1). Two complications occurred in the 19 procedures (10.5%), both transient but significant hemorrhage, one of which necessitated transfusion. Percutaneous biliary ductal shave biopsy with the Simpson atherectomy catheter can be performed successfully through the transhepatic approach and is a sensitive endoluminal biopsy technique, particularly in patients with tumors of the biliary tree that are not diagnosed by means of percutaneous needle biopsy or endoscopic methods. Disadvantages of this method include the high cost of the device and risk of hemorrhage. Atherectomy shave biopsy should be used cautiously and only after more conventional biopsy methods have been employed.