Administered the Halstead-Reitan Battery (HRB) of neuropsychological tests to 24 patients with advanced renal failure, 24 patients with neurological disorders, and 24 patients with medical and/or non-psychotic psychiatric conditions in order to assess the effects of uremic encephalopathy on human neuropsychological functioning. The groups did not differ significantly in age, education, verbal intelligence, or level of affective disturbance. Results indicated that the uremic and neurological groups were equal in overall level of neuropsychological impairment and that both were significantly more impaired than the medical-psychiatric group. However, the uremic group showed a pattern of deficits that was qualitatively different from both the neurological and medical-psychiatric groups. Results were discussed with reference to selective cortical dysfunctions in uremia and contrasted with earlier studies that did not consider differential sparing of abilities in renal patients.