Intrahepatic biliary cystadenoma is a rare disease with only a few reports in the literature. On the other hand, simple hepatic cysts are frequently encountered in daily practice. Unless finding internal septa or mural nodules, we regard the well-defined intrahepatic cystic lesions with homogenous content as simple hepatic cysts. Here we report a 70-year-old woman with multiple, simple hepatic cysts, one of which was biliary cystadenoma. Ultrasound (US) failed to detect the simple cyst mimicker amongst the hepatic simple cysts for one year. Finally abdominal multidetector computed tomography (MDCT) detected the subtle thin internal septa and focal irregular wall, a key feature for the diagnosis of biliary cystadenoma.