Angiotropic large cell lymphoma is a rare microvascular malignancy presenting most commonly with neurologic symptoms but, from a review of the scarce literature, also invariably with evidence of renal involvement. We believe this to be the first case in which the diagnosis was made by initial renal biopsy and in which follow-up of the effectiveness of chemotherapy was assessed by a second biopsy. Proteinuria is prominent in this condition and may result either from the epithelial cell abnormalities associated with the minimal-change lesion or from a direct interaction between the B cell-derived malignant cells and the glomerular endothelium. We believe the kidney may be the most appropriate organ with which to histologically confirm the diagnosis of suspected angiotropic large cell lymphoma and examination of the kidney may prove to be the best way to allow histologic follow-up of the disease or the efficacy of its therapy.