Background and Aim: Measuring the outcome of chronic diseases such as multiple sclerosis is an important factor in assessment of disease impact on different dimensions of quality of life and in evaluation of therapeutic interventions. The aim of this study was to perform the cross-cultural adaptation of the MSIS-29 which is a MS-specific outcome measure for Iranian patients.

Materials and Methods: The Iranian adaptation process of the MSIS-29 included 5 steps. To evaluate psychometric properties of the translated version, the questionnaire was administered to a consecutive sample of 96 patients with clinically definite MS referred to our out-patient clinic. Test-retest reliability was assessed in a sub-sample consisted of 30 patients. These patients completed the questionnaire on two occasions separated by a 7-day interval. The Iranian version of the SF-36 was also administered to this sub-sample in order to evaluate the validity of translated MSIS-29.

 Results: Statistical analysis indicated that the Persian version of the MSIS-29 had high internal consistency (cronbach’s alpha coefficients > 0.70) and test-retest reliability (intra-class correlation coefficients >0.70) and a good validity.

Conclusion: The Persian version of the MSIS-29 is a reliable and valid instrument for measuring MS outcome in Iranian patients. It can be used in clinical trials and cross-sectional studies.