INTRODUCTION: Resistant hypertension (HT) is a common clinical entity with debilitating cardiovascular consequences. The highly heterogeneous nature of resistant HT requires a meticulous workup to exclude 'pseudo-resistance' and secondary forms of arterial HT. Resistant HT has recently gained wide scientific interest due to the introduction of interventional methods (renal sympathetic denervation and carotid baroreceptor stimulation) for blood pressure (BP) reduction in this patient population. Despite however the recent advances in understanding the pathophysiology and the clinical characteristics of the disease, the appropriate management of resistant HT remains elusive. The marked heterogeneity of BP response to interventional therapy underlines the need for careful patient selection and the identification of ideal candidates for interventional therapy.CONCLUSION: The renin-angiotensin-aldosterone system seems to play a cardinal role in the pathophysiology of resistant HT and requires appropriate management. Furthermore, primary aldosteronism is considered the most common form of secondary HT, with increased prevalence in patients with resistant HT. This review aims to provide a simplified work-up for patients with resistant HT, summarize the rationale for the determination of renin and aldosterone levels, and critically discuss available evidence on when and how to measure renin/aldosterone in resistant HT.