BACKGROUND The management of stones in the common bile duct in the laparoscopic era is controversial. The three major options are preoperative endoscopic retrograde cholangiography (ERCP), laparoscopic exploration of the common bile duct (LECBD), or postoperative ERCP. METHODS Between August, 1995, and August, 1997, 471 laparoscopic cholecystectomies were done in our department. In 427 (91%), satisfactory peroperative cholangiography was obtained. In 80 (17%) of these cases there were stones in the common bile duct, 40 patients were randomised to LECBD and 40 to postoperative ERCP. If LECBD failed, patients had either open exploration of the common bile duct or postoperative ERCP. If one postoperative ERCP failed, the procedure was repeated until the common bile duct was cleared of stones or an endoprosthesis was placed to prevent stone impaction. The primary endpoints were duct-clearance rates, morbidity, operating time, and hospital stay. Analyses were by intention to treat. RESULTS Age and sex distribution of patients was similar in the randomised groups. Duct clearance after the first intervention was 75% in both groups. By the end of treatment, duct clearance was 100% in the laparoscopic group compared with 93% in the ERCP group. Duration of treatment was a median of 90 min (range 25-310) in the laparoscopic group (including ERCPs for failed LECBD) compared with 105 min (range 60-255) in the postoperative ERCP group (p = 0.1, 95% CI for difference -5 to 40). Hospital stay was a median of 1 day (range 1-26) in the laparoscopic group compared with 3.5 days (range 1-11) in the ERCP group (p = 0.0001, 95% CI 1-2). CONCLUSIONS LECBD is as effective as ERCP in clearing the common bile duct of stones. There is a non-significant trend to shorter time in the operating theatre and a significantly shorter hospital stay in patients treated by LECBD.