Materials and Methods: In order to use the FIS in Iranian patients, the forward  and backward translation and assessing the patient's perspective was done and the Persian version of the questionnaire was prepared.

Results: The questionnaire was completed by twenty patients with multiple sclerosis. The time duration of filling out of each questionnaire took ten to twenty minutes .The final corrections was carried out. All questions of patients was acceptable and understandable and questions of "sexual activity" was completed only by married patients. The question of "financial support" was completed only by employed person (working people). Finally, as much as possible, this questionnaire was adapted with Iranian culture and sentences were confirmed by MAPI Institute.

Conclusion: Persian version of the FIS is an appropriate tool for measuring the impact of fatigue, effectiveness of treatment and rehabilitation interventions on fatigue in patients with multiple sclerosis.