ACEIs are widely prescribed antihypertensives and have become the mainstay of therapy for severe CHF. Nevertheless, a focused AII-receptor blockade has compelling intellectual appeal and substantial clinical advantages over the ACEIs (no disruption of the prostaglandin and bradykinin biosystems). Identification and careful characterization of the AII receptors and the recent discovery of their antagonists has led to the extensive clinical investigation of selective AII-receptor blockers in both hypertension and severe CHF. Studies with the first orally active AII-receptor blocker, losartan, have demonstrated safe and effective control of elevated blood pressure and improvement of the abnormal hemodynamics typical of pronounced CHF. Several other oral AII-receptor blockers are currently being evaluated, and early results with these agents are encouraging.