Abstract: The subject of this research is the peculiarities of age and gender structure of urban population of South Siberia over the period from 1945 to 2017. Territorial framework include the national republics o Khakassia, Tuva, and Altai; the year 1945 is selected as the chronological boundary as benchmark of a relatively stable period in the Russian history, after the end of the Great Patriotic War. The selection of chronological framework was also affected by the entry of Tuvan Autonomous Oblast into the RSFSR in 1944. The goal of this article lies in examination of the development vectors of age and gender structures of urban population in the indicated republics for the formation of general picture of demographic trajectory of urban population of the region, as well as the prospects for its development in the nearest future. The research is prepared on the basis of statistical data of five All-Union and two Russian censuses, as well as current census registration presented on the official website of the Russian Federal State Statistics Service (http://www.gks.ru). Demographic development of urban population of South Siberia along with its age and gender structure has not been a subject of separate scientific research. Although it is necessary to conduct such analysis for the socioeconomic planning and development of the region, as well as for the regional historical science, because the impact of demographic processes upon the history of particular communities is an old-established fact. The study demonstrated a nonuniform distribution of urban population by age and gender, which significantly affected such demographic processes as birth rate and mortality rate.