Treatment of hypertension in the elderly: effects on blood pressure, heart rate, and physical fitness. The subjects were 36 hypertensive patients aged 61 to 79 years (mean, 66 years). After a placebo run-in period of one month, each patient was randomly assigned to two months of treatment with 100 mg of metoprolol, 50 mg of captopril, or 25 mg of hydrochlorothiazide plus 2.5 mg of amiloride daily, or placebo. The doses were doubled if diastolic pressure was above 95 mm Hg after one month of treatment. Blood pressure, heart rate, and physical fitness (endurance during a standard cycle ergometer exercise) were measured and side effects assessed after each two-month treatment period. Mean blood pressures were significantly lower after treatment with metoprolol (154/92 mm Hg), captopril (157/92 mm Hg), and hydrochlorothiazide-amiloride (152/91 mm Hg) than after placebo (170/101 mm Hg). Heart rate was significantly lower after treatment with metoprolol (64 beats/minute) than after placebo (77 beats/minute). Exercise endurance was lower after treatment with metoprolol (498 seconds) and hydrochlorothiazide-amiloride (519 seconds) than after placebo (529 seconds) and higher after captopril (541 seconds). More patients reached the target exercise work load after captopril than after the other treatments. No patients withdrew from treatment because of side effects or abnormal laboratory test results. All three active treatments benefited the elderly hypertensive patients and did not lower their physical fitness. Captopril appeared to be more effective than the other two treatments. 