Choledochal cysts are single or multiple cystic dilatations throughout the biliary system. Bile duct cysts can cause serious complications such as ductal stenosis, stone formation, cholangitis, secondary biliary cirrhosis, cyst rupture, and cholangiocellular carcinoma. The bile duct cyst classification system takes into account the location and number of cysts, as well as the presence of abnormal pancreaticobiliary ductal conjunction. The typical presentation of choledochal cysts includes the triad of abdominal pain, jaundice, and a palpable mass. However, most patients present with only 1 or 2 of the triad. Patients may also report nausea, vomiting, fever, pruritus, and weight loss. Choledochal cysts may also be detected incidentally during prenatal ultrasonography or in asymptomatic patients who undergo imaging or endoscopic retrograde cholangiopancreatography (ERCP) for other reasons. Biliary cysts are associated with an increased risk of malignancy, particularly cholangiocellular carcinoma. Overall, the reported incidence of cancer is 10-30%, although published reports may overestimate the true incidence. Cancer is more common in older patients and in patients with type I and IV cysts. Patients with type II or III cysts have a lower risk of developing cancer. Cancer has been reported to occur in 7%-15% of patients with type V cysts. Choledochal cysts are usually diagnosed by cross-sectional imaging. Additional tests may be needed to rule out biliary obstruction or to confirm that the cyst is connected to the biliary system (MRI) Treatment of patients with bile duct cysts depends on the type of cyst and the presence of symptoms in the patient. In cysts with high malignant potential, removal of the cyst reduces (but does not eliminate) the risk of malignancy. In addition to reducing the risk of malignancy, cyst removal also reduces complications such as recurrent cholangitis, choledocholithiasis, and pancreatitis. In patients with type I or IV cysts, we recommend complete surgical resection of the cyst and Roux-en-Y hepaticojejunostomy. If left unattended, type I or IV cysts carry a high risk of malignancy. Choledochal cysts have now been classified as choledocholithiasis. The current view is that once choledochal dilatation is detected, there is both an indication for surgery. In patients with abnormal pancreaticobiliary junction (APBJ) without cysts, we recommend prophylactic cholecystectomy rather than expectant treatment.Patients with APBJ have an increased risk of gallbladder cancer. In patients who have undergone complete cystectomy, it is reasonable to perform annual liver serology to screen for biliary anastomotic strictures at the anastomosis. Patients with malignancy in the resected cyst may require additional treatment and follow-up.