Acute lymphoblastic leukemia (ALL) is the most and Wilms tumor is the sixth most common malignancy in childhood. Genetic changes in WT1 or WT2 in Wilms tumor and a wide range of chromosomal mutations are reported in ALL that may predispose them to other congenital anomalies especially in Wilms tumor patients. Hospitalized patient was a 3-year-old girl with high-grade fever, petechia, and solid abdominal mass. The patient had anemia, thrombocytopenia, and leukocytosis in her initial homogram, and a large renal mass originated from left kidney in abdominal imagings. Bone marrow aspiration revealed ALL, and simultaneous kidney biopsy uncovered her Wilms tumor. Leukemia and Wilms tumor are 2 independent malignancies but occurred together in this patient. It is reasonable to investigate cellular and genetic relation of these 2 independent malignancies.