Resistant hypertension is defined as elevated blood pressure that remains beyond the goal despite the concurrent use of at least 3 antihypertensive drug classes, of which one is a diuretic, administered at maximum or maximally tolerated daily doses. Ten per cent of all hypertensive patients are treatment resistant and thus at a higher risk of hypertension-mediated organ damage, cardiovascular events and all-cause mortality. They are also very likely to have a secondary cause of hypertension. The diagnosis requires assurance of medication adherence and ambulatory or home blood pressure monitoring. Treatment should include appropriate lifestyle changes and discontinuation of any drugs that elevate blood pressure. Spironolactone is the fourth-line drug of choice. If not well tolerated, another potassium sparing diuretic, doxazosin or bisoprolol, should be considered. Hydralazine or minoxidil could be used for additional therapy in case blood pressure remains above goal.