OBJECTIVE A serious complication of hepatic hydatid cyst disease is communication between the cyst and the biliary tree. Surgical management of biliary fistulas is associated with high morbidity and mortality. We carried out a prospective study of endoscopic management of hydatid cysts communicating with bile ducts in 28 patients. METHODS Presence of biliary fistula was suspected by jaundice and/or persistent external biliary fistula after surgical excision and was confirmed by endoscopic retrograde cholangiopancreatography (ERCP). Patients underwent endoscopic sphincterotomy, and either biliary stenting or nasobiliary drainage. Nasobiliary drains were removed when bile leakage stopped and closure of the fistula was confirmed by cholangiography; stents were removed after 4-6 weeks. RESULTS Of 120 patients with hepatic hydatid cyst seen over a 10-year period, 28 patients developed fistula between the hepatic hydatid cyst and intrahepatic bile ducts (right intrahepatic bile ducts in 20 patients, left intrahepatic bile ducts in eight patients). Nine of 28 patients had persistent external biliary fistula after surgery. Ten patients showed membranes in bile ducts on cholangiography. We carried out either sphincterotomy with insertion of a nasobiliary drain (n=6) or sphincterotomy with biliary stenting (n=22). In 10 patients, the membranes were removed from bile ducts during ERCP. Fistulas healed in all patients after a median time of 11 days (range 5-45 days) after endoscopic treatment. We were able to remove nasobiliary drainage catheters and stents 8-45 days after placement. CONCLUSIONS Endoscopic therapy is an effective mode of treatment for biliary fistulas complicating hepatic hydatid cyst.