Endoscopic sphincterotomy (ES) was performed on 27 patients after cholecystectomy with a T tube in situ at a mean interval of 23 days after surgery. A precut papillotomy facilitated deep cannulation and subsequent standard ES in three patients with impacted ampullary stones. Bile duct clearance was successful at the first attempt in 22 of 25 (88%) patients who had common bile duct stones. Spontaneous passage of the stones occurred in two patients within 10 days of ES, while the T tube was still in situ. In one patient, the T tube had to be removed to facilitate spontaneous passage of the stone through the ES opening. Choledochoduodenal fistula occurring immediately above the ampulla of Vater was found in three (11%) of our patients. Common bile duct exploration is the most likely cause of these fistulae. Mild bleeding in one patient was the only complication encountered. It is concluded that ES is a relatively safe and efficient way of treating common bile duct stones with a T tube in situ.