In hypertension, consideration of systolic blood pressure (SBP) and pulse pressure (PP) is now well recognized from epidemiological and therapeutical points of view, after numerous years of interest in only diastolic blood pressure. SBP, and also PP, are tightly linked to mechanical properties of large arteries. It is now possible to investigate precisely, with very good repeatability, these mechanic properties. The REASON study is an international multicenter randomised, controlled, parallel-groups study in essential hypertensives. The very low dose perindopril/indapamide combination (Per/Ind: 2 mg/0.625 mg) was compared with atenolol (50 mg) for a 12-month active treatment period in terms of blood pressure reduction efficiency and change in large artery hemodynamics to attempt to relate changes in pressure and changes in arterial mechanics. 471 patients suffering from hypertension were included, 406 benefitted from the treatment for one year (per-protocol analysis) and 96 benefitted from arterial investigations (pulse wave velocity and aortic wave reflection with applanation tonometry). Changes in brachial and central SBP and PP were higher with Per/ind than with atenolol. The reduction in pulse wave velocity was similar with both drugs, but aortic wave reflections were more reduced with Per/Ind than with atenolol. The very low dose perindopril/indapamide decreases SBP and PP to a larger extent than does a betablocker after a 12-month treatment. Changes in arterial mechanics, non invasively measured, were the same (pulse wave velocity) or in favour of Per/Ind vs atenolol (higher reduction in aortic wave reflection, with higher reductions in central systolic and pulse pressures).