en پژوهشي Original Research Articles <p dir="ltr" style="text-align: justify;"><strong>Objectives:</strong> This study was designed to evaluate the psychometric features of the Persian version of the Fatigue Impact Scale (FIS-P) tool when used in Iranian MS patients.</p> <p dir="ltr" style="text-align: justify;"><strong>Methods:</strong> 140 MS patients and the equivalent number of healthy controls completed the following assessments: FIS-P, Fatigue Severity Scale (FSS), SF-36 questionnaire and&nbsp; the Mini-Mental State Examination (MMSE).&nbsp;</p> <p dir="ltr" style="text-align: justify;"><strong>Results:</strong> A significant inverse correlation between FIS and the quality of life (SF-36 assessment tool), as well as a positive and significant correlation with the FSS were noted. The Intraclass Correlation Coefficient (ICC) values for the inter-rater reliability for the physical, cognitive, and social sections and the whole questionnaire were 0.89, 0.86, 0.95 and 0.98, respectively. The FIS Persian version was shown to possess a high reliability (with a Cronbach&rsquo;s alpha&nbsp; of 0.953). Likewise, the ICC values for the test-retest reliability were 0.86, 0.87, 0.92 and 0.93 for the physical, cognitive, social subscales and the whole questionnaire, respectively. This suggested a high reliability for the FIS-P.</p> <p dir="ltr" style="text-align: justify;"><strong>Discussion: </strong>With a proper validity and reliability, the Persian-version of FIS retains the capability for being used in the assessment of fatigue and evaluation of the treatment and rehabilitation effects on fatigue-related symptoms among Persian-speaking patients with MS.&nbsp;</p> Multiple sclerosis, Fatigue, Fatigue impact scale, Psychometric, Persian 32 38 http://irj.uswr.ac.ir/browse.php?a_code=A-10-422-1&slc_lang=en&sid=1 Marzieh Heidari : heidariot@gmail.com No Tehran University of Medical Sciences, Tehran, Iran. Seyed Massood Nabavi seyedmassoodnabavi@gmail.com No Department of Neurology, School of Medicine, Shahed Medical University, Tehran, Iran. Malahat Akbarfahimi Akbarfahimi.m@iums.ac.ir Yes Department of Occupational Therapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran. Masoud Salehi salehi74@yahoo.com No Department of Statistics and Mathematics, School of Health Management and Information Sciences, Iran University of Medical Sciences, Tehran, Iran. Mohammad Torabi-Nami torabinami@sums.ac.ir No Department of Neuroscience, School of Advanced Medical Science and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran.