Acute lymphoblastic leukemia (ALL) accounts for approximately 30 percent of all childhood cancer. Leukemic infiltration is generally present in the bone marrow, liver and spleen. It is uncommon to demonstrate infiltration to the kidneys as an initial presenting feature. We present the case of an 11-year-old boy who presented with back pain, without peripheral evidence of bone marrow involvement, who was found to have bilateral renal masses and 70 percent leukemic blasts upon bone marrow evaluation.