We report a case of histopathologically confirmed benign lipoblastoma in the retroperitoneum. The tumorpresented itself as an ill-defined low density mass on a simple radiograph, as a highly heterogeneous echogenicmass on US, and fatty density mass separated by unenhanced linear septa of soft tissue density on CT. The wellcircumscribed and encapsulated tumor was totally removed by operation. CT is considered the modality of choice forcharacterizing lipoblastoma and demonstrating its location and boundary. When there is fatty density mass in theretroperitoneum of a children, the possibility of lipoblastoma should be considered first.