The aims of this study were to investigate the cognitive function of Chinese amyotrophic lateral sclerosis (ALS) patients. Twenty-two patients with ALS were enrolled and a group of 60 healthy individuals were enrolled as a control group. The Extended Scale for Dementia (ESD) was used to evaluate cognitive function and the Hamilton Depression Scale was used for the assessment of depression. In addition, the Modified Norris Scale was used to assess medulla oblongata and limb function. The overall ESD scores were significantly lower in the ALS patients; however, no correlation was found between individual scores of cognitive function and the overall Modified Norris Scale scores. A majority of ALS patients had significantly reduced cognitive function, suggesting the pathological involvement of areas in the brain outside the motor area. This study shows that through the assessment of cognitive function, abnormalities in cognitive function in ALS patients can be identified.