A 27 years old female presented with diffuse abdominal pain, malaise, weight loss and a palpable mass in the left abdomen. Abdominal CAT scan showed a 18 cm heterogeneous tumoral mass that originated in the kidney. The patient was operated on and it was not possible to completely remove the mass. In the postoperative period the patient received chemotherapy with vincristine, cyclophosphamide and adryamicin but the disease progressed and the patient died 16 months later. The pathological study of the surgical specimen disclosed a tumor with monotonous proliferation of small round cells with a basophilic nucleus and scanty cytoplasm with PAS positive granules. Immunohistochemistry was positive for specific neuronal enolase and CD99. Involvement of the urinary system with primary neuroectodermal tumors is very infrequent (Rev Méd Chile 2001; 129: 191-95).