Amyotrophic lateral sclerosis (ALS), traditionally considered as a disorder limited to the motor system, is increasingly recognized to be a multisystem disease, involving associative areas in addition to the motor cortex and therefore affecting cognition. ALS patients may present with subtle behavioural and executive dysfunctions or, less frequently, with a manifest frontotemporal dementia. Event-related potentials (ERPs) are a high-temporal resolution technique, which can be used to explore the presence of cognitive dysfunction. All the primary studies reviewed here have shown ERP abnormalities in groups of non-demented patients affected by sporadic ALS compared to healthy controls. The ERP results support findings of neuropsychological and imaging studies. Prospective studies combining simultaneous neuropsychological and imaging investigations are needed to assess the possible role of ERPs in the early detection and follow-up of cognitive dysfunction in ALS patients.