The presence of oral inflammation has recently been linked with the pathogenesis of cardiovascular diseases. Endothelial dysfunction is considered one of the pathogenetic mechanisms of a whole range of cardiovascular diseases. In the study describes links between periodontitis and endothelial dysfunction. 32 patients (16 boys and 16 girls) with periodontitis and 60 healthy children were examined. Flow-mediated vascular dilatation data were measured in all patients. Flow-mediated dilatation was 9,78±3,16% in children with periodontitis, and 12,85±3,48% in healthy children (p<0,05). Area under the dilation curve was larger in healthy children, then in children with periodontitis, 710±121%·с in comparison with 519±175%·с (p<0,05). An inverse correlation was found between flow-mediated dilatation, area under the dilation curve and periodontitis duration (r = -0,71, -0,77). A negative correlation was found between flow-mediated dilatation, area under the dilation curve and worsening of periodontitis (r = -0,70, -0,71). This study did not demonstrate association between periodontal disease in children and arterial hypertension, coronary heart disease, heart failure. However, the identified endothelial dysfunction requires protective therapeutic and preventive measures. Given the insignificant symptoms of chronic periodontitis in the examined children, it is important to activate efforts aimed at early detection and treatment of this disease. Further research is needed to clarify the prognostic role of endothelial dysfunction in chronic periodontitis.