['To test the hypothesis that a reduction in left ventricular mass by long-term antihypertensive treatment, possibly associated with an improvement of diastolic function, would increase exercise performance in patients with essential hypertension. DESIGNS After a placebo run-in period, 27 patients with essential hypertension World Health Organization stages I and II were assigned randomly to 6-month double-blind treatment with either a diuretic (hydrochlorothiazide plus triamterene) or a converting enzyme inhibitor (trandolapril), to which the calcium antagonist amlodipine could be added after 3 months if required for better blood pressure control.', 'Investigations included clinic and ambulatory blood pressure measurements, left ventricular imaging and transmitral Doppler echocardiography and graded maximal exercise testing on the bicycle ergometer with respiratory gas analysis.', 'Six-month antihypertensive therapy, which caused significant (P < 0.001) reductions in blood pressure (by 16% for clinic pressure) and in left ventricular mass (by 13%), but without convincing evidence of improved diastolic function, did not affect exercise performance or peak oxygen uptake. The influence on clinic, exercise and ambulatory blood pressures and on the peak oxygen uptake was similar in the two treatment arms but left ventricular wall thickness decreased to a greater extent in the trandolapril group (P< 0.05 at 3 months and P= 0.06 at 6 months).'] Does reduction of left ventricular mass by antihypertensive treatment improve exercise performance in essential hypertension?