Mecamylamine (Inversine), the first orally available antihypertensive agent, is now rarely used. Introduced as a therapeutic agent for the treatment of hypertension in the 1950s, mecamylamine was the first useful ganglionic blocking agent that was not a quarternary ammonium compound. Mecamylamine is indicated for the management of moderately severe to severe essential hypertension and in uncomplicated cases of malignant hypertension. Mecamylamine reduces blood pressure in both normotensive and hypertensive individuals. A small oral dosage often produces a smooth and predictable reduction of blood pressure. Although this antihypertensive effect is predominantly orthostatic, the supine blood pressure is also significantly reduced. Mecamylamine is a nicotinic parasympathetic ganglionic blocker. Mecamylamine administration produces several deleterious side-effects at therapeutically relevant doses. As such, mecamylamine’s use as an antihypertensive agent was phased out, except in severe hypertension. Mecamylamine easily traverses the blood-brain barrier to reach the central nervous system (CNS), where it acts as a nicotinic acetylcholine receptor (nAChR) antagonist, inhibiting all known nAChR subtypes. Since nAChRs play a major role in numerous physiological and pathological processes, it is not surprising that mecamylamine has been evaluated for its potential therapeutic effects in a wide variety of CNS disorders, including addiction.