The article analyzes the reproductive and migration processes, as well as the quantitative, spatial, gender, and age dynamics of the Jewish population in the Don region. It identifies the main periods of its geodemographic evolution in the 19th – early 21st centuries and examines the specificities of the settlement system and gender structure of urban and rural Jews. It has been established that the high level of urbanization and sociocultural modernization of the Don Jews activated the process of assimilation as early as at the beginning of the 20th century. Demographic losses of the community during the World War II predetermined its accelerated decline in the post-war period and further intensified assimilation tendencies. The reverse side of the growing assimilation since the 1920s–1930s has been the process of absolute growth and specific expansion of the regional group of mixed population with Jewish roots, which has not been recorded by the official statistics. For certain periods of the 20th – beginning of the 21st century, an assessment of this latent demographic component has been carried out. It is established that by the end of the 20th century, this group repeatedly exceeded the size of the ethnic core of the regional community and is currently a significant factor in the demographic reproduction and sociocultural life of the Jewish population of the Don region.