Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal disorder of bone marrow. It is characterized by blood cells lacking membrane proteins that are normally attached by the glycosylphosphatidylinositol (GPI) anchor. The cellular defect arises in a hematopoetic stem cell and is due to somatic mutation of the Phosphatidylinositolglycan protein-A gene (PIG-A gene), encoding a protein needed for the biosynthesis of the anchor GPI. Paroxysmal nocturnal hemoglobinuria is presented by intravascular hemolysis, cytopenias, frequent infections, bone marrow hypoplasia, and a high incidence of life threatening venous thrombosis. Kidney involvement is usually benign and secondary to chronic tubular deposition of hemosiderin. Acute renal failure may occur in association with a hemolytic crisis. Here we report a case of 40-year-old woman with hematuria, pancytopenia, and acute renal failure due to PNH.