Introduction. The causes of infant mortality in the Republic of Buryatia in different age periods, including those caused by external causes, have not been fully investigated, especially the violent ones. That is why this problem is still urgent, as it is of a social and completely preventable nature. Study. To estimate the mortality rate of the children of the Republic of Buryatia in different age periods, with an emphasis on losses from external causes between 2009 and 2019. Material and methods. We used 2009-2019 data of the Territorial Body of the Federal State Statistics Service in the Republic of Buryatia, information and analytic materials of Russian and foreign authors, including those published on the Internet. The study was conducted using statistical and analytical methods, as well as by comparative analysis. Results. Infant mortality and mortality of children aged 0-4 years prevail in the age structure of infant mortality in the Republic of Buryatia. The leading causes of under-5 and infant mortality during the study period were individual conditions arising in the perinatal period, congenital malformations and external causes. Moreover, external causes are significant not only in adolescence but also in infancy. Suicides, traffic injuries, mechanical asphyxia, drowning and carbon monoxide poisoning are the leading external causes. Discussion. The prominent feature of the regional demographic situation is a high infant mortality, which in different years is higher than in the country, from 6% to 22,7%. In spite of child mortality reducing by all classes of reasons, including external causes, the specific weight of children died of so called non-medical causes remains high: suicides (from 14,1 % to 30,8 %), transport injuries (from 5,5 % to 22,5 %), mechanical asphyxia (from 9,9 % to 26,4 %), drowning (from 10,9 % to 23 %), carbon monoxide poisoning (from 5,4 % to 15,5 %). According to M. Brenner, a leading expert on the socio-economic determinants of mortality, economic growth has been the main factor behind the decline in mortality. Socio-economic risk factors of high frequency of some external causes, especially suicides, include low living standards and insufficient social protection of the population, unemployment, and situations of economic stress. In 2019, Buryatia ranked 69th in the ranking of Russian regions in terms of the population's income level. The region had 20.1% of residents below the poverty line (RF - 12.3%), with 3.1% below the extreme poverty line (RF - 1.9%), the ratio of median income to the cost of a fixed set of goods and services was 1.31 (RF - 1.65). Conclusions. Due to the high mortality rate of older children as a result of injuries, it is necessary to take measures in such spheres as education, transport and road infrastructure, public order protection, interdepartmental cooperation, a set of preventive measures aimed at reducing the causes of death of children from congenital anomalies and more extensive screening for congenital and hereditary diseases of the metabolism in the neonatal period.