Objective: to identify signs of endothelial dysfunction of the cardiovascular system in overweight and obese children. Materials and methods: Comprehensively examined 52 children and adolescents aged 8 to 16 years with exogenous constitutional obesity. Results: In the study of endothelial dysfunction, an excess of recognized markers was revealed: albuminuria (AU), endothelin-1 (ET-1), von Willebrand factor (VWF) activity, and IL-6 levels in the group with obesity and changes in the cardiovascular system compared with comparison group. And also revealed a decrease in the secretion of adiponectin in obesity. Conclusions. Endothelial dysfunction and metabolic syndrome are closely linked and form a continuous cycle leading to metabolic and cardiovascular diseases.