Terazosin (Hytrin; Abbott Laboratories, North Chicago, IL) is a new, selective alpha 1-adrenoceptor blocking agent used on once-a-day basis for therapy of mild-to-moderate hypertension. Its pharmacologic properties are similar to those of prazosin. Terazosin however, differs from prazosin in that its water solubility is 25 times greater than that of prazosin and its elimination half-life is about three times that of prazosin. Greater water solubility facilitates intravenous formulation, and longer half-life allows once-daily administration of terazosin. Terazosin is effective in lowering blood pressure and has a beneficial effect on plasma lipid profile. The major advantage of terazosin compared with prazosin, however, is its long duration of action. Terazosin is safe and effective when used in combination with diuretics and other antihypertensive agents, and in the long-term treatment of patients with mild to moderate essential hypertension.