It is now recognized that left ventricular hypertrophy (LVH), often associated with hypertension, is itself a risk factor for coronary disease in the elderly. Although many agents are capable of controlling blood pressure, the ability of these agents to induce regression of left ventricular (LV) mass, and the effect of regression on diastolic relaxation and contractile indices in the elderly are less well known. Our study compared the ability of the calcium blocker, verapamil, and the beta-blocker, atenolol, to both control blood pressure (BP) and to induce regression of LV mass in older hypertensives. In addition, the influence of regression on resting diastolic filling and on cardiac output and ejection fraction during rest and mild upright bicycle exercise were determined. Forty-two hypertensives 60 years of age or above, without evidence of ischemic disease underwent 2-D echocardiographic evaluation of LV mass and gated blood pool scan determination of early diastolic filling, cardiac output and ejection fraction. They were then randomized to receive verapamil or atenolol during a four-week titration period so as to achieve a BP of less than 160/90 mm Hg. If BP was not controlled with either agent, chlorthalidone was added. Individuals whose BP was controlled continued on the protocol for six months. At that time, the echocardiographic and gated blood pool studies were repeated both on and after subsequent withdrawal of the study medications. Twenty-one patients were randomized to receive verapamil and 21 patients to receive atenolol. Blood pressure control was achieved with verapamil alone in 18 patients, but with atenolol alone in only 8 patients (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)