Choledochal malformations (also known as choledochal cysts) may be characterised as an abnormal dilatation of the biliary tract, in the absence of any acute obstruction. Most appear to be of congenital origin probably related to distal bile duct stenosis, and almost 15% can now be detected antenatally. Excision and biliary reconstruction using a Roux loop as an open operation is still the standard to compare to. This article discusses recent advances in the understanding of their aetiology and classification together with the place of newer modalites of surgical treatment such as laparoscopic excision and biliary reconstruction. Although these are definitely feasible and safe, care should be taken before dispensing with standard open techniques which have minimal complications and proven long-term benefit.