Twenty-eight patients underwent fiberoptic T-tube tract choledochoscopy for the diagnosis, management, and treatment of filling defects seen on postoperative T-tube cholangiograms. In 22 patients, 59 retained stones were treated by extraction. In six other patients with diagnostic problems arising from cholangiogram defects, the diagnosis was made by direct vision and biopsy specimen examination. There were multiple papillary adenocarcinomas in one patient, and normal mucosal folds in two patients. The procedure was accompanied by a low complication rate, with two patients developing pancreatitis and five patients developing transient fever. The advantages of the procedure are a direct examination of the biliary tree with the facility to remove stones and biopsy lesions under direct vision.