A study was undertaken to elucidate the existence of cognitive and memory impairments in patients with amyotrophic lateral sclerosis (ALS) by comparing a group of ALS patients with both nonneurological medical controls (MC) and healthy controls (HC) on neuropsychological tests. We also examined the relationship between the severity of motor disabilities and intellectual impairment. Twenty-two ALS patients, 18 MCs and 17 HCs participated. The tests used were the Mini-mental state examination (MMS) and the immediate and delayed memory tests. The mean MMS score of the ALS patients was lower than the mean scores of both control groups. In the memory tests, there were significant differences between the ALS group and the two control groups. Correlation analyses of several motor symptoms and neuropsychological results revealed that there was a significant negative correlation between upper motor neuron symptoms and MMS, as well as memory tests. The evidence for multisystem degeneration in ALS has prompted speculation that more sensitive neuropsychological measurements might reveal cerebral dysfunction in ALS patients who are not presenting evident dementia.