PURPOSE: To compare the findings of MR cholangiography with those of ultrasound and biochemistry in patients with suspected choledocholithiasis, and to evaluate the clinical utility and role of MR cholangiography prior to laparoscopic cholecystectomy. MATERIALS AND METHODS: We retrospectively reviewed the radiologic findings and clinical records of 103 consecutive patients in whom choledocholithiasis was suspected and who underwent both ultrasound and MR cholangiography. For MR imaging, a 1.5T unit was used, and axial T1-FLASH, True FISP, and oblique coronal HASTE and RARE images were obtained. Initial biochemical values (AST, ALT, total bilirubin) were correlated with the findings of MR cholangiography. RESULTS: Choledocholithiasis was present in 36 of 103 patients: overall, there were 34 true-positive, 63 truenegative, four false-positive, and two false-negative results. In the detection of choledocholithiasis, MR cholangiography showed the following characteristics: sensitivity, 94%; specificity, 94%; positive predictive value, 89%; negative predictive value, 96%; accuracy, 95%. Calculi in the common bile duct were detected in 3 of 33 patients (9%) in whom ultrasound showed that the caliber of the common bile duct was normal and whose laboratory findings were normal, and in 12 of 43 (28%) of those whose common bile duct was dilatated or whose laboratory values were abnormal. Calculi were present in the common bile duct of 21 of 27 patients (78%) with abnormal laboratory values and abnormal ultrasound findings. CONCLUSION: Choledocholithiasis was detected in 25% of patients without clinical suspicion and was not present in 25% of patients with strong clinical suspicion. In patients with this condition, MR cholangiography is noninvasive and accurate, and we suggest that in patients with suspected choledocholithiasis, it should be a routine diagnostic procedure prior to laparoscopic cholecystectomy.