Biliary cystadenomas are rare cystic neoplasms of the biliary ductal system. Cystadenomas have a tendency to recur, particularly following their incomplete excision, with the potential for malignant transformation. Cystadenocarcinomas are very rare and; despite complete resection, can recur in a short time. A cystadenoma cannot be easily differentiated from a cystadenocarcinoma preoperatively or intraoperatively; therefore, complete surgical resection should be always considered. Four biliary cystadenoma and one biliary cystadenocarcinoma cases, treated at the Kyung Hee Medical Center, between 1998 and 2003, are reported. The patients were comprised of one man and four women, with a mean age of 45 years. Four patients presented with abdominal pain or jaundice, and the other was asymptomatic, with an incidentally discovered liver tumor. Preoperative CT scans demonstrated a multilocular cyst in four patients and a choledochal cyst-like appearance in the other. All patients underwent complete excision. One cystadenoma arose in the extrahepatic bile duct and the other four appeared in the liver. A histological examination revealed a mesenchymal stroma, which resembling ovary, in two cystadenomas. None of the four patients with a cystadenoma developed a recurrence. However, the patient with a cystadenocarcinoma underwent two pulmonary wedge resections for pulmonary metastases 14 and 21 months after the liver resection.