Among patients with resistant hypertension, primary aldosteronism (PA) is worth detecting as it appears to be particularly common in this cohort. It is associated with excessive cardiovascular morbidity in relation to the degree of hypertension and reduced quality of life, both of which can be abrogated with specific surgical or medical treatment. Knowledge concerning factors (including medications) which can influence the results of screening by aldosterone/renin ratio (ARR) testing is expanding, and is important to appreciate, particularly in patients with resistant hypertension, in whom the need for multiple medications can render interpretation challenging. Advances in approaches to confirmatory testing, subtype differentiation and assay methodology are helping to improve feasibility and reliability of the diagnostic workup for PA and new treatment approaches are emerging. Major developments in understanding the genetic bases for PA hold promise towards further improvements and options in diagnosis and therapy.