We present a case of cancer of a choledochal cyst in a patient with antecedents of cholecystectomy, who complained of pain in the right hypochondrium. Echography and CAT disclosed a cystic mass of biliary location, and the diagnosis was confirmed by intraoperative cholangiography and biopsy of the cyst margin. Cysto-jejunostomy on a Roux-en-Y loop was performed. The patient survived 11 months and died of tumoral dissemination. We reviewed 130 cases of cancer of a choledochal cyst published up until 1986 and possible etiopathogenic causes, and we discuss the diagnostic problems and related treatment.