We report a case of non-Hodgkin lymphoma (NHL) with acute renal failure. A 62-year-old man was admitted to our hospital on March 8, 2002 with leg edema and dyspnea on effort. About 3 weeks before admission, he was found to have slightly high serum creatinine (Cr) and high lactate dehydrogenase (LDH) levels by another home doctor. Physical examination revealed anemic conjunctivae and leg edema, but the urinary volume was preserved. Blood examination showed high BUN (64 mg/dl) and Cr levels (3.91 mg/dl). Urinary analysis showed proteinuria (1.05 g/day) and high BMG (14,434/microg/day) and NAG (4.55 U/day) levels, suggesting severe tubulointerstitial injury. On ultrasonography of the kidney, the bilateral kidneys showed marked swelling without hydronephrosis. To investigate the genesis of renal failure, we performed a renal biopsy. The specimen showed normal glomeruli, but a large number of cells infiltrated in the tubulointerstitial area with normal tubulointerstitial structure. The cells stained positively with anti-leukocyte antigen and L26 (B cell marker), and negatively with cytokeratin and UCHL-1 (T cell marker). These findings indicate that the interstitial cells were non-Hodgkin lymphoma with B cell diffuse large cells. Chemotherapy was performed with VAD (vincristine sulfate, doxorubicin hydrochloride, dexamethasone) considering his renal dysfunction. To avoid tumor lysis syndrome after chemotherapy, hemodialysis was performed on days 1-4 after the initiation of chemotherapy. After a series of chemotherapy, the urinary volume increased and serum Cr levels decreased to 2 mg/dl. After additional therapy with 4 courses of CHOP, he improved and was discharged on day 180 after admission.