Hepatic angiomyolipoma is a rare, benign, hepatic mesenchymal neoplasm. We report a case of an extremely large hepatic angiomyolipoma in a 58-year-old woman with unusual sonographic features. The tumor was well demarcated from the surrounding liver and showed a heterogeneous cystic appearance with a thick echogenic rim. Color Doppler showed blood flow in the echogenic rim and around the lesion. Contrast sonography demonstrated strong enhancement in the solid rim from early arterial phase to the late phase and no enhancement in the central cystic part of the lesion. Spiral CT showed a well-defined huge heterogeneous cystic mass with fatty density. At surgery the tumor was soft and encapsulated with a thin, smooth membrane. The cut surface of the tumor revealed a cystic appearance with necrotic tissue. The diagnosis of hepatic angiomyolipoma was confirmed by immunohistochemistry.