Title: Effect of juvenile essential arterial hypertension on nitric oxide-dependent endothelial dilation in skin microcirculation Objectives: The main objective of this study was to functionally determine the effect of essential arterial hypertension in children on the nitric oxide-dependent endothelial dilation in forearm skin microcirculation. Study Design: The study was designed as a cross-sectional observational study. Participants and Methods: The study involved 52 subjects of both sexes, aged 7 – 18 years, who were split into two groups, normotensive (NT) group – which included 26 children/adolescents who had normal blood pressure values, and hypertensive (HT) group – which included 26 children/adolescents who had essential arterial hypertension. Hemodynamic and anthropometric measurements were conducted, including measurements of blood pressure, pulse, body height and weight, as well as both waist and hip circumference. Using the results, BMI and WHR were calculated. Samples of venous blood were taken for analysis. Forearm skin microcirculation reactivity was assessed with LDF in response to local heating and transdermal application of SNP. Results: The values of systolic, diastolic and mean arterial pressure, as well as BMI, were significantly higher in children/adolescents who had essential arterial hypertension compared to the normotensive group. Statistically significant difference in WHR and pulse values was not observed between groups. Subjects in the HT group had a significantly weaker microcirculation response to LTH compared to the NT group. Endothelium-independent vasodilation induced with SNP did not significantly differ between groups. Conclusion: Essential arterial hypertension is in children associated with reduced endotheliumdependent microcirculation vasodilation mediated by NO, while it does not influence endothelium-independent vasodilation.