Adrenal cavernomas are rare benign tumors, and those of giant dimensions are exceptional. Usually, they are symptomless or they induce symptoms and signs due to compression over nearby organs. We present the case of a 68-year-old woman, who complained of abdominal enlargement and abdominal pain in the left part of the abdomen. Imagistic investigations (native and contrast abdominal computed tomography) revealed an inhomogeneous retroperitoneal mass of 210∕182∕200 mm, containing calcifications. Laboratory findings were not relevant, just a slight and non-significant elevation of carcinoembryonic antigen and a slight elevation of C-reactive protein. Diagnosis of cancer of undetermined origin was considered, and surgery was performed. During surgery, a giant encapsulated inhomogeneous tumor of 330 mm, with cystic areas, was removed, without assessing the origin. Primary or secondary tumors (metastasis from breast, intestinal, lung, renal or skin cancer) were taken into account. Only histopathology and immunohistochemistry revealed the diagnosis of adrenal cavernoma. Until this moment, we found only one published article in the medical literature with similar dimensions of an adrenal cavernoma as in our case. Even if rare, hemangioma of the adrenal gland must be considered during the differential diagnosis of an adrenal tumor.