Acute tubulointerstitial nephritis usually develops due to either acute infection of kidneys or delayed hypersensitivity reaction to medication and may rarely be associated with acute renal failure. The disease may very rarely be associated with hematologic/neoplastic diseases. Tubulointerstitial nephritis associated with leukemia is usually due to chemotherapeutic agents or viral infections of the severely immuno-compromised host mostly after bone marrow transplantation. We herein report 2 cases of acute tubulointerstitial nephritis associated with acute leukemia. To our knowledge, the cases are the first in literature in which acute tubulointerstitial nephritis was simultaneously diagnosed with acute leukemia without any chemotherapeutic insult or apparent viral infection. Despite the usual asymptomatic nature of the disease process, the cases are original in that acute tubulointerstitial nephritis associated with acute leukemia resulted in acute renal failure in both cases and hemodialysis was inevitable in one.