OBJECTIVES: The primary objective of this study was to determine the influence of essential arterial hypertension in children on the vascular reactivity of microcirculation of the forearm skin, as well as defining the role of oxidative stress in the said vascular response. STUDY DESIGN: This is a cross-sectional observational study. PARTICIPANTS AND METHODS: In this research 26 subjects were involved, children aged from 8 to 17 of both sexes, that were divided into two groups, based on (non)existence of essential arterial hypertension (NT group - normotensive children and HT group - hypertensive children). BMI, waist / hip ratio, arterial pressure and pulse were measured for all subjects, and samples of venous blood and 24-hour urine were taken. Furthermore, microvascular reactivity of the forearm skin was also assessed in all subjects by measuring flow with LDF in response to occlusion and iontophoretic application of ACh and SNP. RESULTS: The values of SBP, DBP and MAP were significantly higher in the HT group, while BMI waist / hip ratio and heart rate did not differ between the groups. The value of sodium in the 24-h urine sample was statistically significantly increased in the HT group compared to the NT group, as was the calculated daily intake of sodium chloride. In children suffering from essential arterial hypertension, the increase in flow in the skin microcirculation in response to occlusion and ACh application was significantly reduced, while there was no difference between the studied groups in endothelium-independent vasodilatation induced by SNP. In the HT group, the measured value of 8-iso-PGF2α was significantly increased compared to the NT group. CONCLUSION: Essential arterial hypertension in children significantly reduces endothelium-dependent vasodilation in the microcirculation of the skin, while it does not affect endothelium-independent vasodilation. Oxidative stress is significantly increased in children suffering from essential hypertension compared to healthy children with normal blood pressure values.