Paroxysmal nocturnal hemoglobinuria (PNH) is a rare cause of hemolytic anemia. The major outlines of clinical presentation comprises findings of hemolysis, venous thrombosis and findings of bone marrow failure. The presentation of the disease with acute kidney injury (AKI) is not frequent. Massive hemoglobinuria following a serious attack of hemolysis during the course of PNH may lead to AKI by way of causing acute tubular necrosis. Hemoglobin casts and accumulation of hemosiderin in the proximal tubule may be seen in renal biopsy. The treatment is not different from that of acute tubular necrosis. Herein, we present a case who was admitted to our clinic with AKI and diagnosed to have PNH during hospitalization.