We describe a case of peripheral T cell lymphoma that is remarkable for its fulminate course and selective targeting of both kidneys. The patient was a 6-year-old girl who was in her usual state of good health until the onset of abdominal pain and fever. She was treated for acute oliguric renal failure and visual disturbances. A renal biopsy was performed. Biopsy findings were interpreted as suggestive of a vasculitic process, and treatment was initiated for a presumptive diagnosis of Wegener's granulomatosis. The patient died 3 days following admission, and autopsy revealed extensive bilateral kidney infiltration by a peripheral T cell lymphoma. The remainder of the body was spared with the exception of mild infiltration of the pulmonary parenchyma and choroid plexus by neoplastic lymphocytes. The neoplastic nature of the disease was confirmed utilizing immunoperoxidase stains and T cell receptor gene rearrangement. Primary renal lymphoma and renal failure attributable to involvement by lymphoma are rare findings that should be considered when other more common causes of renal insufficiency have been excluded. The presenting clinical complaints are generally of short duration, nonspecific, and atypical. Most patients exhibit oliguria. Physical examination may reveal hepatosplenomegaly, lymphadenopathy, and flank and/or abdominal mass(es). Laboratory findings frequently include an elevated serum creatinine, blood urea nitrogen, lactate dehydrogenase, and a mild proteinuria. Electrolyte abnormalities are variably present. Possible radiographic findings include hypodense or hypoechoic renal lesions and diffuse bilateral renal enlargement. Although the prognosis is dismal, survival may be prolonged utilizing current treatment modalities, and rare patients may be "cured" of disease. The clinical presentation, radiological findings, and prognosis of patients with clinically evident renal involvement by non-Hodgkin's lymphoma are discussed.