Objective. This study provided an objective survey by an outside auditing group of a large, complete patient population undergoing laparoscopic cholecystectomies, determined the frequency of complications, especially bile duct injuries, and presented a system for classifying and comparing the severity of bile duct injuries. Summary Background Data. This is the first study of laparoscopic cholecystectomy to encompass a large and complete patient population and to be based on objectively collected data rather than self-reported data. The Civilian External Peer Review Program (CEPRP) of the Department of Defense health care system conducted a retrospective study of 5642 patients who underwent laparoscopic cholecystectomies at 89 military medical treatment facilities from July 1990 through May 1992. Methods. The study sample consisted of the complete records of 5607 (99.38%) of the 5642 laparoscopic cholecystectomy patients. Results. Of the sample, 6.87% of patients experienced complications within 30 days of surgery, 0.57% sustained bile duct injuries, and 0.5% sustained bowel injuries. Among 5154 patients whose procedures were completed laparoscopically, 5.47% experienced complications. Laparoscopic procedures were converted to open cholecystectomies in 8.08% of cases. Intraoperative cholangiograms were attempted in 46.5% of cases and completed in 80.59% of those attempts. There were no intraoperative deaths; 0.04% of the patients died within 30 days of surgery. Conclusions. The frequency of complications found in this study is comparable to the frequency of complications reported in recent large civilian studies and earlier, smaller studies. The authors present a system for classifying bile duct injuries, which is designed to standardize references to such injuries and allow for accurate comparison of bile duct injuries in the future.