The renin-angiotensin system regulates blood pressure and sodium homeostasis through a series of coordinated substrate-enzyme interactions. These interactions result in the production of angiotensin II (AII), which exerts a number of diverse biologic effects mediated through AII cell-surface receptors. Dysregulation of this system is implicated in the pathogenesis of various forms of hypertension. Traditional therapy for hypertension has included angiotensin-converting enzyme inhibitors, which block the production of AII. However, a new class of drugs, AT1-receptor blockers, now offers a number of benefits by specifically blocking the effects of AII at its physiologically relevant receptor.