The amyotrophic lateral sclerosis (ALS) is a degenerative neurological disorder that has a great impact in the quality of life of the patients. This study had the objective of validating the ALS Assessment Questionnaire in the Portuguese Language (ALSAQ-40/BR). The version of ALSAQ-40/BR, was adapted into the Portuguese language after the evaluation and re-evaluation of 20 patients with a defined ALS diagnosis. The demonstration of its reproducibility and reliability makes this instrument an additional and useful parameter which can be used in the evaluation of ALS for research or assistance.