Biliary cystadenoma and cystadenocarcinoma are rare neoplasms of the biliary ductal system. The authors present 2 cases of biliary cystadenoma and 3 cases of cystadenocarcinoma. The typical sonographic appearance of these tumors is a large intrahepatic globular or ovoid thick walled cystic mass which often contains multiple septations with papillary growth and solid portion. Low-level internal echoes may be seen within the cystic mass. The characteristic CT findings of these tumors are multiloculated cystic mass, thick septations with papillary projections and solid portion within the cystic mass. Angiographical characteristics of theses tumors are hypovascular mass with frequet abnormal clusters of tumor vessels within the walls on arterial phase and accumulation of contrast material along the wall or internal septation on delayed film.