Multiple sclerosis is a classic multifactorial disease in which etiology interaction of external factors and structural features of a large number of genes plays an important role. Identifying risk factors for multiple sclerosis and creating an integrated model of pathogenesis are urgent tasks of neurology. Revealing true risk factors is possible only in studies with sufficient statistical power, so with a large amount of samples. We conducted the association study of CD40 gene's polymorphisms and multiple sclerosis among residents of the Russian Federation. The results demonstrated the need to combine data from different researchers in clinical studies to increase the power of the study.