Twenty-one male patients affected by ALS have been given a short neuropsychological battery and the results have been compared with those obtained by 21 male subjects affected by other non-dementing neurological diseases. Only two ALS patients had definitely low scores on WAIS (performance scale) and on learning tasks, both verbal and spatial, but the ALS group did not differ, on the whole, from the controls. No relationship was observed between cognitive impairment and cerebral atrophy assessed by computerized tomography. The conclusion is suggested that the cognitive impairment in ALS be a discrete, seldom occurring event.