In pediatric oncology patients, hemorrhagic cystitis can be a life-threatening complication of bone marrow transplantation, chemotherapy, and radiation therapy. The treatment of this condition is often challenging and includes intravesical irrigation with aluminum, embolization, endoscopic laser coagulation, hydrostatic pressure, use of hyperbaric oxygen, instillation of formalin, prostaglandins, and oral sodium pentosan polysulfate. Although the efficacy of aluminum irrigation is well documented for the management of hemorrhagic cystitis in adults, there are limited reports describing its use in children. The potential multisystem toxic effects of aluminum are well described and the range and progression of aluminum toxicity can be devastating. We report a case of a 9-year-old girl suffering from acute lymphocytic leukemia with hemorrhagic cystitis. Although the symptoms resolved after intravesical aluminum treatment, she developed significant aluminum toxicity. We have reviewed the literature relating to aluminum toxicity in the pediatric age group and present our recommendations for the effective and safe use of aluminum in this cohort of patients.