Facing the relentless worsening of their condition, ALS patients are required to make decisions on treatments and end-of-life care. A cognitive impairment showed to be a negative prognostic factor in ALS patients, perhaps affecting the ability to make informed decisions. Notwithstanding its crucial role, the capacity to consent to treatment (CCT) has never been evaluated in these patients.To assess the CCT in an ALS cohort in comparison to a control group, and to study the effects of demographic and clinical variables on this high-level cognitive function.102 ALS patients and 106 healthy controls (HC) were enrolled. CCT was assessed using the MacArthur Competence Assessment Tool for Treatment (MAC-CAT-T) and the performance was classified into the three CCT outcomes (full credit, partial credit, no credit). Cognitive and psychological variables were assessed by MMSE, phonemic fluencies, Frontal System Behavioural Scale (FrSBe), and ALS Depression Inventory (ADI). Clinical and demographic variables were analyzed as possible predictors of the MAC-CAT-T outcomes. After a 1-year follow-up, CCT and neuropsychological assessments were repeated.Most ALS patients (i.e., from 75 to 83% according to the different sub-items) retain full CCT. However, a subpopulation of the ALS patients showed a reduced CCT with respect to the HC. Age, education, phonemic fluency, and depression appeared related to the CCT outcomes. After 1 year, only the reasoning items worsened.This is a preliminary report suggesting that the large majority of ALS patients can retain full ability to choose between treatment options. However, demographic and neuropsychological variables may affect CCT, pointing to the need for special attention to the consent disclosure in this disease.