Among patients with renal failure, there have been impressive modifications of both the duration and quality of life as a result of dialysis, renal transplantation, and improved medical management. However, patients who have renal failure continue to manifest a variety of neurologic disorders. Patients with chronic renal failure who have not yet received dialytic therapy may develop a symptom complex progressing from mild sensorial clouding to delirium and coma, with tremor, asterixis, multifocal myoclonus, and seizures. Even after the institution of otherwise adequate maintenance dialysis therapy, patients may continue to be afflicted with more subtle nervous system dysfunction, including impaired mentation, generalized weakness, and peripheral neuropathy. The central nervous system disorders of both untreated renal failure and that persisting despite dialysis are referred to as uremic encephalopathy. The dialytic treatment of end stage renal disease has itself been associated with the emergence of two distinct, new disorders of the central nervous system: Dialysis dysequilibrium and dialysis dementia. The dialysis disequilibrium syndrome consists of headache, nausea, muscle cramps, obtundation and seizures, and is a consequence of the initiation of dialysis therapy in some patients. Dialysis dementia is a progressive, generally fatal encephalopathy which affects patients on chronic hemodialysis. This disease also appears to be a complication of the therapy for renal failure.