Objective：To investigate the diagnosis and treatment of congenital choledochal cysts in adults.
Methods：The records of 78 cases of congenital choledochal cyst in adults seen in the last 10 years were retrospectively analysed.
Results：Among the 78 cases, 74 patients under went operation: (1)52 cases had total cyst excision and Roux-en-Y hepatojejunostomy; (2)9 cases had partial cyst excision and Roux-en-Y hepatojejunostomy; (3)2 cases had duodenopancreatectomy; (4)Among 11 cases with cancer, 1 case underwent duodenopancreatectomy, 7 cases had radical resection of cholangiocarcinoma and 3 cases had palliative external drainage; (5)1 case had external drainage for bleeding and  rupture of choledochal cyst. Among the 74 cases, 54 patients were followed-up, the rate of follow-up was 73.0%. Follow-up period was 2 months to 7 years, mean 39 months. Patients with benign disease were in excellent condition. Among malignant disease patients, 1 case had duodenopancreatectomy, was lost to follow-up; 5 of the 7 cases with radical correction of cholangiocarcinoma were followed up and the survival time was  2-5 years, with the median survival time of 2.3 years. Three cases,  who had palliative external drainage, had a survival of 2-16 months, with the median survival time of 7.8 months.
Conclusions：Adult congenital choledochal cyst is prone to develop cancer. Early diagnosis and early treatment of congenital choledochal cyst is the key, and surgical excision of the cyst and bilioenterostomy are the basic principles of treatment.