Introduction. Obesity is a multifactorial disease that arises through the joint actions of multiple genetic and environmental factors. Identification of genetic markers of obesity, including their polymorphisms, especially in children of early and preschool age is an important field of diagnosis and prevention of the disease.Aim. To study the prevalence of single-nucleotide polymorphisms of the gene (AGT: с.174C>T, p.T174M (rs4762) and AGT: с.235T>С, p.M235T (rs699)) in children with obesity.Materials and methods. A total of 180 children aged 5–17 years were examined in a clinical case-control study. The case group included 120 obese subjects, of whom 60 were aged 5–10 years old and 60 were aged 11–17 years old. The control group included 60 subjects with normal body weight, of whom 30 were aged 5–10 years old and 30 were aged 11–17 years old. The subjects underwent measurement of physical development, carbohydrate metabolism, and lipid status, as well as daily blood pressure monitoring, and molecular genetic testing, in particular, gene polymorphisms (AGT: p.174C>T, p.T174M (rs4762) and AGT: p.235T>C, p.M235T (rs699)). Odds ratios (OR) and their 95% confidence intervals (CI) were calculated to assess the impact of polymorphisms on the development of obesity and obesity-associated conditions. Results. No association was established between the AGT gene polymorphism: c.174C>T and obesity and dyslipidemia in children aged 5–17 years old. We found an association between the AGT gene polymorphism c.235T>C and obesity and dyslipidemia in children aged 5–17 years old (OR 3.1 [0.1; 3.9], p = 0.000001; OR 1.6 [0.9; 3.3], p = 0011). An association between both polymorphisms and the development of arterial hypertension (AH) in children and adolescents with obesity (OR 1.2 [0.4; 2.7], p = 0.000025; OR 2.2 [0.5; 2.4], p = 0.00002) was established.Discussion. Numerous works performed by foreign authors demonstrated the association between the AGT gene polymorphism: p.235T>C and the development of obesity and related comorbid conditions in adults. There is no information on the effect of the AGT polymorphism: p.174C>T.Conclusion. The renin-angiotensin-aldosterone system (RAAS) gene polymorphisms contribute to the development of obesity, dyslipidemia and hypertension in childhood.