From 1974-8, 808 postoperative choledochoscopy procedures, conducted by insertion of choledochofiberscope into the biliary tract through the sinus tract after the T-tube had been removed, were carried out in 292 patients at Teikyo University Hospital, Tokyo, Japan. In this series, 104 with retained biliary tract stones were encountered, and complete removal of stones was successfully carried out in 101, using postoperative choledochoscopy. Any failures of removal of retained biliary tract stones were attributed to improper insertion of the T-tube. The T-tube, of at least 18 French calibers should be inserted into the common bile duct at a right angle so as to obviate a tortuous sinus tract. THe follow-up study in cases of complete extraction of the retained biliary tract stones showed that this approach is most effective. Recurrent stone with a silk nidus was found in one patient in whom postoperative choledochoscopy had been performed one year previously. Reoperation was carried out in this particular case. All other patients have remained asymptomatic. Finally, we advise routine use of postoperative choledochoscopy as an adjunct to the T-tube cholangiography, in order to prevent the possibility of retained biliary tract stones.