Currently the ubiquitous increase of multiple sclerosis (MS) prevalence is observed. The increase in number of patients with MS is marked also in the areas where MS prevalence was low previously, so the assessment of multiple sclerosis risk factors in populations with low multiple sclerosis risk is of a great value. There were no investigations of demyelinating disease epidemiology performed in the Republic of Ingushetia (RI) before. The purpose. To perform the clinical and epidemiological study of MS in RI; to study the factors, affecting the risk of MS development in RI population. Material and methods. We examined 73 patients (46 women and 27 men) with reliable MS (according to McDonald criteria, 2010, 2017). The investigation of risk factors of MS development was carried out by the method of analytical epidemiology «case-control». All respondents were inhabitants of RI, the pairs were comparable in age, gender and nationality. We studied serum concentration of vitamin D3 metabolite — 25(ОН)D3 by ELISA method. Results. Prevalence of NS in RI was 14.4 cases for 100 thousand of the population as of 1.01.2020. Among MS patients we revealed a higher frequency of contact with petrol and oil products (12 of 73 respondents vs 2 of 61 in groups of MS patients and control group respectively, р < 0,05), and paints (15 of 73 respondents vs 2 of 61 in groups of MS patients and control group respectively, р < 0,05), aged over 15 years old. Reliably more often than persons of control group MS patients have a case of surgical interventions, severe caries at the age over 15 years old (р < 0,05), head injury at any age (р < 0,05), tonsillitis, measles, rubella, parotitis occurred at the age before 7 years old (р < 0,05) and herpetic infection at any age (р < 0,05). According to the comparison of vitamin D3 metabolite — 25(ОН)D3 serum concentration parameters in MS patients of both sexes of RI population and control group we revealed a tendency to decrease of serum vitamin D level in MS patients; the differences in this feature in men with MS (15,15 (0,61) ng/ml) and men of control group (22,04 (8,0) ng/ml) were statistically reliable. Conclusion. The Republic of Ingushetia belongs to the areas of low-mild multiple sclerosis development risk, which is probably due to both demographic and geographical-climatic features. The external factors of MS development risk revealed in this research confirm the multifactor nature of the disease. Further investigations of the probable modifiability of these factors are of great importance.