Congenital cystic dilation of the biliary tree is rarely considered as cause of cholangitis in the adult patient. Emergency operation in seven adults with unsuspected choledochal cysts resulted in reoperation in all seven. Each patient presented with right upper quadrant pain, a mass, and cholangitis or jaundice. Abdominal ultrasonography incorrectly identified the cyst as a dilated gallbladder in three of the patients. All initial emergency drainage procedures required subsequent modification to cyst excision and Roux-Y reconstruction. From review of the experience presented and the literature to date, we recommend that otherwise stable patients be managed nonsurgically and undergo endoscopic retrograde cholangiopancreatography or percutaneous transhepatic cholangiography to plan primary single-stage excisional operation. Patients requiring emergency decompression should have cholecystostomy or choledochostomy for good control without compromising subsequent operation. At the time of excision, a technical consideration not previously reported is the presence of small daughter cysts in Calot's triangle which must be distinguished from the hepatic bile ducts. The surgical literature has frequently addressed the problems of elective surgery for choledochal cysts; however, emergency complications requiring urgent operative intervention are seldom addressed. We believe emergency intervention should correct the urgent complication without compromising the definitive surgical treatment.