BACKGROUND:Choledochal cysts are classified into five types based on the location of the cyst.Mixed types of choledochal cysts are extremely rare.Only five cases of mixed typeⅠandⅡcholedochal cysts have been reported, of which one was an adult case.We report a mixed typeⅠ andⅡcholedochal cyst in a 25-year-old man. METHODS:The unusual nature of the choledochal cyst, suspected on magnetic resonance cholangiopancreatography RCP to be typeⅠinitially,was confirmed by laparotomy to be a mixed typeⅠ+Ⅱcyst.Excision of the cyst and hepaticojejunostomy were performed. RESULT:The operation was uneventful,and the patient recovered well. CONCLUSIONS:Mixed type choledochal cysts are rare, and may be missed on imaging,unless careful evaluation is done.The operative method may not need to be modified significantly,as in the management of our case. BACKGROUND: Choledochal cysts are classified into five types based on the location of the cyst. Mixed types of choledochal cysts are extremely rare. One of the five cases of mixed type I and IIcholedochal cysts have been reported, of which one was an adult case. We report a mixed type I METHODS: The unusual nature of the choledochal cyst, suspected on magnetic resonance cholangiopancreatography RCP to be type I in vitro, was confirmed by laparotomy to be a mixed type I + II cyst. Excision of the cyst and hepaticojejunostomy were RESULT: The operation was uneventful, and the patient recovered well. CONCLUSIONS: Mixed type choledochal cysts are rare, and may be missed on imaging, unless careful evaluation is done. The operative method may not need to be modified significantly, as in the management of our case.