OBJECTIVE This study was designed to present the radiological imaging findings of a renal primitive neuroectodermal tumor (PNET). METHODS The study included 10 patients with pathologically proven renal PNETs. We assessed the size, margin, internal architecture, enhancement pattern, vein thrombosis, and presence of a metastasis of the tumors on multidetector-row computed tomography and magnetic resonance imaging. RESULTS The mean age of the patients was 31 years. Patients were predominantly male (males-females, 8:2). The mean diameter of a renal PNET was 12.7 cm. All masses were well defined with a lobulated contour. Necrosis and hemorrhage were detected in 9 cases, respectively. All of the masses showed weak heterogeneous enhancement with multiple irregular septumlike structures. Eight of the masses had renal vein thrombosis, and 4 masses had extension into inferior vena cava. A lymph node metastasis was detected in 3 patients. A lung metastasis was detected in 4 patients, and 2 of the patients also had a bone metastasis. CONCLUSIONS A renal PNET usually appears as a weakly enhanced large mass with multiple septumlike structures, peripheral hemorrhage, venous thrombosis, and accompanied with a distant metastasis in a young adult.