Antihypertensive therapy significantly reduces cardiovascular morbidity and mortality in the rapidly growing population of elderly patients. However, the desire to treat more of these patients is dampened by the concern that a reduction in blood pressure may compromise cerebral blood flow, causing untoward consequences. This study evaluated the therapeutic effect of titrated doses of prazosin, an alpha-adrenergic blocking agent, on systemic blood pressure and cerebral blood flow in elderly patients with chronic stable hypertension. Prazosin alone or co-administered with hydrochlorothiazide significantly lowered mean systolic and diastolic blood pressures in 31 elderly hypertensive patients. At the same time, however, there was no significant change in cerebral blood flow, which was measured in eight patients. Neither harmful biochemical changes nor treatment-related adverse effects were observed in any patients. Prazosin therapy alone or in combination with low-dose diuretic therapy was effective in the treatment of hypertension in this elderly population. Furthermore, blood pressure reduction with prazosin therapy was accomplished without compromising cerebral blood flow and without unfavorably altering lipid profiles.