44 men with treated essential hypertension who were moderate to heavy drinkers took part in a randomised, controlled, crossover trial of the effects of alcohol intake on blood pressure. Usual antihypertensive treatment was maintained throughout 6 weeks of normal drinking and 6 weeks of drinking only a low-alcohol beer. Self-reported changes in alcohol consumption (mean [SEM] from 452 [30] ml ethanol/week during normal drinking to 64 [8] ml/week while drinking the low-alcohol beer) were confirmed by biochemical measurements. Mean systolic and diastolic blood pressures were significantly lower during the last 2 weeks of the low-alcohol period than during the normal-alcohol period, the mean difference in the supine readings being 5.0 (1.4) and 3.0 (0.9) mm Hg, respectively. Regression analysis suggested that reduction in alcohol intake contributed to the fall in both systolic and diastolic blood pressures independently of changes in weight. Thus, curtailing alcohol intake may lead to improved blood-pressure control and may reduce the need for antihypertensive drugs.