Introduction: This study aimed to determine the validity and reliability of the Persian version of the Arm Function in Multiple Sclerosis Questionnaire which is a self-report questionnaire for persons with multiple sclerosis (MS). Method: This methodological study was performed in the following stages: translation, validity, internal consistency, and test–retest reliability of Persian-AMSQ. The Nine-Hole Peg Test (9HPT), Coin Rotation Task (CRT), and Functional Independence Measure (FIM) for construct validity were used. Psychometric testing was done to ascertain the validity and reliability of the questionnaire. Results: In this study, 155 people with MS participated. There were no major linguistic or cultural difficulties in the translation of AMSQ. Face and content validity confirmed by experts and people with MS. The internal consistency was high (Cronbach’s α = 0.99). Test–retest reliability, as measured with intra-class coefficient, was 0.98. Correlations with 9HPT (r = 0.54), CRT (r = 0.16), and FIM (r = −0.54) were significant (p < 0.05). Conclusion: The Persian-AMSQ appears to be a valid and reliable questionnaire for measuring upper extremity dysfunction in MS.