OBJECTIVE The aim of this study was to determine useful predictive factors of common bile duct stones (CBDs) as diagnosed by endoscopic retrograde cholangiopancreatography (ERCP) in patients who underwent laparoscopic cholecystectomy (LC) for gallstones. METHODS A total of 510 patients underwent ERCP prior to LC. Also reviewed in each were clinical data, laboratory data, and ultrasonographic findings. Data were evaluated by uni- and multivariate analysis to determine which of the useful predictive factors thus far reported might be in the concurrence of CBDs. RESULTS Univariate analysis identified jaundice, pancreatitis, ALT, total bilirubin, alkaline phosphatase, amylase, and CBD dilatation at ultrasonography as predictors. Multivariate analysis subsequently identified alkaline phosphatase (p<0.0001), total bilirubin (p=0.0008), amylase (p=0.0009), and CBD dilatation at ultrasonography (p=0.0012) as independent predictive factors of CBDs. The estimates for the detection of CBDs, when the indication of ERCP is determined on the basis of the four predictive factors, were found to be as follows: sensitivity 97.6%, positive predictive value 78.6%, and positive accuracy 95.3%. CONCLUSIONS It is advisable to ascertain by preoperative ERCP whether there might be any CBDs in patients about to undergo an LC for treatment of cholelithiasis insofar as the patient has one or more of these factors. It is concluded that an LC may be performed by omitting the prior ERCP, conversely, on patients devoid of all of these factors.