BACKGROUND: Various studies on the prediction of common bile duct (CBD) stones through preoperative or operative cholangiography have been reported. When CBD stones were suspected due to preoperative screening factors, endoscopic retrograde cholangiopancreatography was done as a first choice and operative cholangiography could be omitted. We want to know the indications of selective cholangiography and the significance of routine operative cholangiography during a simple cholecystectomy. METHODS: The cases of 134 patients who received on open cholecystectomy between Jan. 1995 and Sept. 1997 were reviewed. Twenty-even (27) cases of a choledocholithotomy without cholangiography were discarded from this study. Our cases were divided into two groups: group I included 9 patients who had CBD Stones, which was pathologicaly confirmed by operative cholangiography, and group II included 98 patients who had no CBD Stones, which pathologicaly confirme by operative cholangiography. The predictability of pathologic CBD. was calculated by the factors as the total bilirubin, alkaline phosphatase, AST, ALT, GGT, CBD. diameter by sonography. According to the number of positive screening factors, 3 grades of scoring were imposed in each case. Grade I was the case where 0- screening factor was positive, grade II was the case where 2 screening factors were positive, and grade III was the case where 3 or more screening factors were positive. RESULTS: Eighty-ive (85) cases were grade I, 6 cases were grade II, and 16 cases were grade III. In grade I, only one case had asymptomatic CBD stones, and the negative predictability was 98.8%. In grade II, there were no CBD lesions, and the negative predictability was 100%. In grade III, there were 8 cases of pathologic CBD lesions, and the negative predictability was 50%. CONCLUSIONS: Precise prediction of CBD lesions before a cholecystectomy is of value in deciding whether or not to perform an operative cholangiography. In our study, we graded the patients according to 5 non-nvasive screening factors. In grade I cases, the negative predictability of 98.8% was acceptable for omitting the operative cholangiography. In grade II cases, the negative predictability was 100%, but in these cases, there was the possibility of pathologic CBD Stones. Hence, in these cases, an operative cholangiography may be done, depending on the surgeon's decision. In grade III cases, an operative cholangiography or a preoperative ERCP. is mandatory.