BACKGROUND: With the advent of laparoscopic cholecystectomy, endoscopic retrograde cholangiography (ERC) is frequently employed before operation to detect common bile duct stones. However, this is an invasive technique with recognized complications. This study evaluated the accuracy of magnetic resonance cholangiography (MRC) to detect choledocholithiasis in selected patients before laparoscopic cholecystectomy. METHODS: Patients scheduled for elective laparoscopic cholecystectomy, with risk factors for common bile duct stones, underwent MRC followed by ERC or peroperative cholangiography. RESULTS: Over a 2-year period 40 patients were studied. MRC had a sensitivity of 88 per cent, specificity of 93 per cent, positive predictive value of 78 per cent and negative predictive value of 97 per cent for the detection of common bile duct stones. CONCLUSION: MRC is a simple non-invasive method for preoperative screening for common bile duct stones in at-risk patients. In this study it would have reduced the need for ERC by three-quarters.