Infant mortality is considered one of the main indicators of the health of the population and is perceived as a kind of indicator of the country's social economic development, the state of the sanitary and demographic state of the population, the quality of medical services, the effectiveness of sanitary and epidemiological, preventive and therapeutic work. The purpose of the research work. Age –gender analysis of infant mortality under three years of age. Material and research methods. In Tashkent, 2017-2019 was studied by observation of children under 3 years of age (total 2041). For a deeper study of the causes of infant mortality, we selected the following age groups that the Jaxon Health Organization adopted and recorded in the International Classification of diseases (2004). Results obtained. The causes of infant death are mainly dominated by diseases of several classes. The causes of infant death under 1 year of age include diseases of the respiratory organs (30.3%), aloxida cases in the perinatal period (29.8%) and a large percentage of congenital anomalies(26.5%). Discussion. Infant mortality under one year of age is considered one of the first regular social issues of the current period, as it represents 89.3% of infant mortality under 5 years of age, 78.5% of infant mortality under 14 years of age, 4.5% of total population mortality, and leads to a sharp decrease in the average life expectancy of the population. Conclusion. The magnitude of infant mortality is strongly influenced by the age of the child, that is, the smaller the age, the higher the indicator. Mortality rates in the Neonatal and postneonatal periods differed sharply. The ratio of the Neonatal and postneonatal mortality rate is 66:34. Among children who die under one year of age, boys and girls have a mortality rate equal to a ratio of 120:100. ; Младенческая смертность считается одним из основных показателей здоровья населения и рассматривается как специфический показатель, показывающий социально - экономическое развитие страны, ...