Hepatobiliaty cystadenoma is an uncommon lesion and it is difficult to diagnose preoperatively. Regardless of the various diagnostic modalities used, cystadenoma and cystadenocarcinoma cannot be differentiated with accuracy. Here we report on a 34-year-old woman who presented with enlargement of a cyst for the previous 6 months. The imagine diagnostic tools revealed a 7㎝-sized cystic mass with irregular multiple septation in her liver. All laboratory tests were normal except serum CA 19-9(62.5u/㎖). Because of the malignant potential, the natural history of progression, enlargement and recurrence after partial excision, a complete surgical excision was performed. The patient was discharged with good recovery and 2 months after surgery her serum CA 19-9 level had returned to normal(32.9u/㎖).