The effects of prolonged infusion of perindopril (1 mg/kg/d) were studied on Goldblatt rats and spontaneously hypertensive SHR rats compared to control animals. Perindopril increased significantly the arterial compliance in treated animals. Mechanical parameters of the carotid artery are normalized with perindopril infusion in renovascular hypertensive rats and improved in SHR rats. Perindopril reversed the thickness of aortic media in treated rats. After three months treatment the ratio elastine/collagen of the aortic media increased significantly. Perindopril reversed the majority of vascular alteration in both hypertensive groups. 2. Twenty one hypertensive patients received for 30 minutes an infusion of perindoprilat either at 1 mg/kg/min, or at 2.5 mg/kg/min, or dihydralazine at 4 mg/kg/min. It was shown that perindoprilat significantly reduced the blood pressure in the three groups. However the increase in arterial diameter and compliance were only recorded with perindoprilat (2.5 mg/kg/min) infusion. The results of this study pointed out that for the same antihypertensive effect, with two different antihypertensive drugs, the vascular effects can be different. Blood pressure, forearm hemodynamic parameters, echocardiography values were recorded on 16 sustained hypertensive patients before and after one year of perindopril treatment. The results showed that perindopril decreased significantly the SBP, DBP and the MBP, increased diameter and arterial compliance of the brachial artery, and decreased cardiac mass. Three months later, the treatment was stopped for four weeks: blood pressure and hemodynamic values returned toward basal values, whereas mass cardiac didn't increase significantly; then the treatment was continued over 9 months; during this period. The arterial compliance increased again on the cardiac mass remained reduced. (ABSTRACT TRUNCATED AT 250 WORDS)