The management of common bile duct (CBD) stones in patients subjected to laparoscopic cholecystectomy is still a subject of debate. A prospective study was performed of all 699 patients with symptomatic gallstones at risk of CBD stones between mid-1987 and 1994. Based on clinical, biochemical and ultrasonographic criteria, 119 patients underwent preoperative endoscopic retrograde cholangiopancreatography (ERCP) with or without endoscopic sphincterotomy. Results showed a high positive predictive value (over 85 per cent) for the presence of CBD stones in patients with acute cholangitis, persistent obstructive jaundice or in the acute phase of gallstone pancreatitis. In the other groups (increased liver enzyme levels, a wide CBD and after resolution of jaundice or pancreatitis) the positive predictive value was less than 25 per cent. The complication rate of ERCP with sphincterotomy was 14 per cent with a mortality rate of 2 per cent. These results argue for more selective use of preoperative ERCP only for patients with acute cholangitis, persistent jaundice or acute gallstone pancreatitis. Other patients at risk of harbouring CBD stones should undergo intraoperative laparoscopic cholangiography and, if stones are found, laparoscopic exploration of the bile duct or postoperative ERCP.