To assess the value of preoperative or postoperative endoscopic treatment of bile duct stones and routine use of operative cholangiography (OC) for detection of unsuspected common bile duct (CBD) stones in conjunction with laparoscopic cholecystectomy. Prospective study. University hospital, Sweden. Diagnostic and therapeutic yield of stones at endoscopic retrograde cholangiography (ERC) before or after laparoscopic cholecystectomy and routine operative cholangiography. Of 630 patients who underwent laparoscopic cholecystectomy, 84 had preoperative ERC. Of these 84, 47 (56%) had bile duct stones. Endoscopic sphincterotomy was done for all 47, of whom 3 (6%) had retained stones at OC. OC was done for 590 (94%) of the 630 patients, and 45 (7.6%) were found to have choledocholithiasis. At postoperative ERC, however, 10 of these patients were free of stones and there were two cases of false negative OC, which resulted in sensitivity and specificity of OC of 95% and 98%, respectively. Thus, 35 patients (6%) had bile duct stones discovered at OC, of whom 33 had "unsuspected" stones. Of these 35 patients, 29 were cleared endoscopically after cholecystectomy. The remaining 6 patients were cleared of stones either by open choledocholithotomy (n = 2) or by laparoscopic transcystic manipulation (n = 4). There was no mortality after diagnostic or therapeutic ERC, and morbidity was confined to two cases each of pancreatitis and cholangitis, which resulted in a complication rate of 3% (4/118). No complications resulted from IOC. Preoperative ERC should be done for patients with symptoms or findings indicating ductal calculi. In most patients undergoing laparoscopic cholecystectomy, OC is feasible and its routine use is strongly advocated. Bile duct stones diagnosed at OC can safely and successfully be treated endoscopically after laparoscopic cholecystectomy. Until laparoscopic bile duct exploration becomes routine and generally applicable, endoscopic management of bile duct stones both before and after cholecystectomy will be an important therapeutic option.