Acute renal failure is a well-recognized complication of acute leukaemias. Howevcr, serious renal failure caused by leukaemic infiltration as a primary manifestation is unusual. Here we report two patients with acute lymphoblastic leukaemia presenting with acute renal failure due to leukaemic infiltration. The first patient died before the administration of specific therapy for leukaemia, whereas the second case recovered after chemotherapy. She was discharged without necessitating dialysis therapy.