Systemic arterial hypertension is a serious health problem worldwide. In some cases, it can phenotypically present as resistant arterial hypertension, which consists of blood pressure levels outside the treatment goals in patients using three or more classes of antihypertensive drugs, one of which is preferably a thiazide diuretic. Resistant hypertension contributes to a 47% higher risk of developing cardiovascular events when compared to patients with non-resistant hypertension. It is known that the microcirculation plays a relevant role in the pathophysiology of arterial hypertension. Furthermore, it is known that the cutaneous microvascular network is an adequate model and that it reflects the systemic microcirculation. In this sense, the present research proposes the study of cutaneous capillary density - through high resolution intravital microscopy - and of the endothelium-dependent and independent microvascular vasodilator response - by the speckle laser flowmetry method coupled to a pharmacological system of micro- iontophoresis - in patients diagnosed with resistant hypertension, with the aim of identifying changes in comparison with patients with non-resistant hypertension and normotensive individuals. Additionally, the evaluation of the association between systemic microvascular function and the presence of target organ lesions in this population may indicate that this is a new non-invasive way of stratifying cardiovascular risk in these individuals.