We describe a patient undergoing chronic hemodialysis who developed a neurologic syndrome consisting of seizures, progressive myoclonus, and mild dementia and who responded to chelation therapy with deferoxamine mesylate. Neither her serum nor bone aluminum concentrations indicated aluminum toxicity. However, the presence of a positive deferoxamine-infusion test was suggestive of an elevated body burden of aluminum. Treatment with deferoxamine resulted in marked clinical improvement in her neurologic status within two months. The utility of using the deferoxamine-infusion test rather than serum aluminum levels in evaluating aluminum toxicity in chronic renal failure is suggested.