Preoperative cholangiography and subsequent removal of bile duct stones may increase the efficacy of laparoscopic cholecystectomy and reduce the rate of conversion to open cholecystectomy. Since there is little data on the incidence of choledocholithiasis in this group of patients, we undertook a prospective study on the routine performance of ERC in 288 patients selected for laparoscopic cholecystectomy. ERC succeeded in 264 of the 288 patients (91.7%) and showed a normal bile duct system in 227 (86.0%). Atypical bile duct anatomy was seen in eight patients. Open cholecystectomy was performed in seven of them but was judged to be absolutely necessary in only two cases (one patient each with Caroli syndrome and Mirizzi syndrome). ERC also revealed bile duct stones in 29 of 264 patients (11.0%) which had not been suspected on the basis of clinical, laboratory and ultrasonographic findings in nine cases (3.4%). EPT succeeded in all of the 29 patients with choledocholithiasis but open cholecystectomy was subsequently performed in four patients due to incomplete bile duct clearance (n = 3) or temporary bleeding after EPT (n = 1). The rate of ERC/EPT-related morbidity was 2.8%. It is concluded from a risk-benefit analysis in these patients that ERC should be restricted to patients with suspected bile duct stones. Following this strategy, small ductal concrements and bile duct abnormalities will be missed in 6.4% of cases but the clinical relevance of these findings is still unclear. In patients with combined gallbladder and common bile duct stones, preoperative EPT plus subsequent laparoscopic cholecystectomy appears to be an effective and time-saving therapeutic regimen which should be compared with open cholecystectomy plus common bile duct exploration in future studies.