SummaryThe effect of a combined beta-blocking agent-diuretic therapy on blood pressure and renin-angiotensin has been avaluated. Two protocols have been used in 20 hypertensive patients. In the first one, the diuretic has been administered after a maximum dose of betablockade and in the second, beta-blockers have been given after a constant dose of diuretic. In both cases, the addition of the second drug produced a further fail in blood pressure. Physiopathologically, the drugs are compatible, because the stimulation of the renin-angiotensin-aldosterone system induced by diuretics is countered by beta-blockers.