Untreated essential hypertension leads to cardiovascular and renal disease and stroke, but antihypertensive drug therapy effectively reduces these consequences of hypertension. Several studies indicate that hypertension can negatively impact on cognitive function, especially on learning and memory, but the ability of antihypertensive drugs to ameliorate these cognitive dysfunctions is less clear. None of the recent studies convincingly demonstrates that any of the antihypertensive drugs currently in use has a major deleterious effect on cognition in hypertensive patients, but some of the drugs more reliably benefit cognitive function in the hypertensive patient. As a class, the angiotensin-converting enzyme inhibitors most consistently lead to cognitive improvement in the overall hypertensive population, but beta 1-adrenergic receptor blockers and a subset of calcium channel blockers appear to have very similar effects. Animal studies and clinical studies in demented patients suggest that angiotensin-converting enzyme in the cerebral cortex plays a role in normal learning and memory, a finding that provides a theoretic foundation to the beneficial actions of this class of drugs on cognitive function in hypertensive individuals.