Twenty-nine patients with symptomatic hydatid disease of the liver were evaluated preoperatively by endoscopic retrograde cholangiopancreatography (ERCP) in the years 1982-1987. In the same period, 6 patients who previously underwent surgery for the parasitic disease also underwent ERCP because of postoperative symptoms of biliary obstruction. Findings at ERCP excluded biliary tract involvement in 11 cases. Positive findings were shown in 24 patients, including compression of the bile ducts in 4, small cysto-biliary communications in 5, intrabiliary rupture in 9, residual hydatid material in the common bile duct, and sclerosing cholangitis in 3. Endoscopic removal of migrated hydatid debris was achieved in 8 patients, avoiding reoperation in 4.