Background: As a disease of motor nervous system (motor neuron disease), amyotrophic lateral sclerosis (ALS) has a great impact on several aspects of quality of life (QoL). Generic questionnaires of QoL do not address all the especial features of ALS and therefore translation and validation of disease specific questionnaires such as Amyotrophic Lateral Sclerosis Assessment Questionnaire 40-item (ALSAQ-40) is necessary for assessment of patients with different languages. The aim of this study was to review the validation of the Persian version of the ALSAQ-40.Methods: Meticulously translated ALSAQ-40 was completed by 21 ALS patients. Internal reliability was evaluated using Cronbach’s alpha coefficient and item- total correlation was also used to evaluate the correlation of each question with total score.Validity was evaluated through comparison with Amyotrophic Lateral Sclerosis Functional Rating Scale-revised (ALSFRS-r)and the 36-Itemhort Form Health Survey (SF-36). Results: Cronbach’s alpha coe<cient was 0.91-0.96 for different scales of the ALSAQ-40. All the 40 questions of the questionnaire had correlation greater than 0.5. Correlation coefficient of all the related scales of the Persian version of ALSAQ-40, SF-36 and ALSFRS-r was greater than 0.59 with P value < 0.001.Conclusion: Measures of the Cronbach’s alpha coefficient and item-total correlation demonstrated reliability and consistency of the questionnaire, and correlation coefficients confirmed the validity of different items in the questionnaire. This study showed that the Persian version of the ALSAQ-40 is a reliable and valid questionnaire for the evaluation of QoL in ALS patients with Persian language.