Background: Liver abscess is commonly biliary in origin. We assessed the role of endoscopic retrograde cholangiopancreatography (ERCP) in patients with pyogenic liver abscesses. Methods: Between January 1986 and December 1997, 63 patients with pyogenic liver abscesses were referred for ERCP. Twenty-one patients had a history of previous biliary procedures including cholecystectomy (21), biliary-enteric bypass (9), surgical sphincteroplasty (5), and endoscopic sphincterotomy (2). Demographic data, clinical features, biochemical parameters, treatment, clinical progress, and follow-up were recorded and analyzed. Results: Two patients required laparotomy and 61 patients underwent guided aspiration and/or drainage at a median interval of 3 days after presentation. ERCP was performed at a median of 8 days (range 1 to 69 days) after initial treatment and succeeded in 90% of cases with no associated complication or death. Abnormalities were shown in 29 (46%) patients: biliary obstruction due to stones or strictures (15), ductal dilatation alone (7), spontaneous choledochoduodenal fistula (3), communication between abscesses and biliary tree (3), and splaying of biliary ducts by space-occupying effect (2). No abnormality was found in 34 patients. Eight patients underwent endoscopic therapy including sphincterotomy (5), stone extraction (6), and nasobiliary drainage (2). Overall mortality rate from liver abscesses was 6%. Conclusions: ERCP is useful in the treatment of patients with pyogenic liver abscesses. (Gastrointest Endosc 1999;50:340-4.)