OBJECTIVE. The purpose of this prospective study was to compare the accuracies of laparoscopic sonography and laparoscopic videofluoroscopic cholangiography in detecting common bile duct stones and in identifying ductal anomalies during laparoscopic cholecystectomy. SUBJECTS AND METHODS. Ninety-five patients who underwent laparoscopic videofluoroscopic cholecystectomy were prospectively studied with laparoscopic sonography and laparoscopic videofluoroscopic cholangiography. The number of successful studies, the time required to complete the study, and complications resulting from the study were recorded. The biliary system was evaluated for complete visualization of the common bile duct, visualization of the cystic duct, ductal anomalies, maximum diameter of the common bile duct, and common bile duct stones and/or debris. Also determined was whether laparoscopic sonographic findings altered operative management. RESULTS. Laparoscopic sonography was successfully performed in 93 of 95 patients, and laparoscopic videofluoroscopic cholangiography was successfully performed in 90 of 95 patients. The time required to complete laparoscopic sonography ranged from 3 to 18 min (mean ± SD, 8 ± 3 min), and that required to complete laparoscopic cholangiography ranged from 5 to 28 min (mean ± SD, 14 ± 6 min). Laparoscopic sonography visualized the complete common bile duct in 84 of 93 patients, and laparoscopic cholangiography did so in 86 of 90 patients. Laparoscopic sonography showed the cystic duct in 87 of 93 patients, and laparoscopic cholangiography did so in 80 of 90 patients. Laparoscopic sonography showed no ductal anomalies in any of the 93 patients. Laparoscopic cholangiography showed ductal variants in 13 of 90 patients; however, 11 of the variants were proximal to the sonographic scan plane. Laparoscopic sonography showed common bile duct stones in 12 of 93 patients, and laparoscopic cholangiography did so in five of go patients. Laparoscopic sonography altered operative management in two of 93 patients. CONCLUSION. Our results show that laparoscopic sonography is as accurate as laparoscopic videofluoroscopic cholangiography in visualizing the common bile duct and cystic duct and in detecting common bile duct stones. However, the data are too limited to determine whether laparoscopic sonography is as accurate as laparoscopic cholangiography in detecting ductal anomalies.