Knowledge of the configuration of the extrahepatic bile duct is indispensable to avoid bile duct injury during cholecystectomy. Various methods of examining the biliary tract have been developed; however, the most appropriate preoperative diagnostic modality at cholecystectomy for cholecystolithiasis has not yet been reported. Considering the frequency of bile duct maljunction (BDM) and operative bile duct injury, in addition to the cost and invasiveness of the various examination methods, we evaluated the usefulness of drip infusion cholecystocholangiography (DIC) as the optimal method of examination at cholecystectomy for cholecystolithiasis. Preoperative diagnostic accuracy of BDM was analyzed in relation to operative bile duct injury using 469 patients with benign biliary diseases who was diagnosed with DIC and endoscopic retrograde cholecystography and underwent cholecystectomy. BDM was classified according to Hisatsugu criteria. Out of 469 consecutive patients who underwent a cholecystectomy for biliary stones between January 1, 1995, and September 30, 1998, at Ohta Nishinouchi General Hospital, 21 (4.48%) had a cystic duct maljunction (CDM) and 12 (2.56%) had an aberrant bile duct (ABD). The most common variants were types C and D for CDM, and types II and III for ABD, according to Hisatsugu's classification. Fourteen patients (42.4%) were diagnosed before the surgery; 13 of them received preoperative endoscopic retrograde cholangiography (ERC), and the remaining patient underwent preoperative drip infusion cholecystocholangiography (DIC). Nineteen patients could not be correctly diagnosed based on their preoperative examinations, but were diagnosed during surgery. Operative bile duct injury occurred in 1 patient (0.2%) whose maljunction could not be diagnosed before the operation. Taking into account the medical cost and invasiveness, and the frequency of BDM and related bile duct injuries, we conclude that DIC is an acceptable preoperative diagnostic modality to employ at cholecystectomy for cholecystolithiasis. Knowledge of the configuration of the extrahepatic bile duct is indispensable to avoid bile duct injury during cholecystectomy. Various methods of examining the biliary tract have been developed; however, the most appropriate preoperative diagnostic modality at cholecystectomy for cholecystolithiasis has not yet been reported. Considering the frequency of bile duct maljunction (BDM) and operative bile duct injury, in addition to the cost and invasiveness of the various examination methods, we evaluated the usefulness of drip infusion cholecystocholangiography (DIC) as the optimal method of examination at cholecystectomy for cholecystolithiasis.