We have realized an unicentric prospective study to assess the effects of Nitrendipine on carotid circulation and arterial blood pressure (BP) in essential, permanent, uncomplicated arterial hypertension. This randomized, double blind versus placebo trial concerned 21 mild to moderate hypertensive patients (pts) (WHO advices) aged from 35 to 65 years. After a 15 days washout, the pts were randomized in two groups: 11 pts received a 20 mg Nitrendipine tablet once a day and 10 pts received a placebo. BP control and ultrasonic carotid flowmetry were performed at J0 and J30. At J30, BP was normalized for 55% of pts under NT (versus 30% for placebo). This result correspond to a very significative decrease for systolic and diastolic BP and differential BP (Dif BP) without reflex tachycardia, under Nitrendipine, opposite to placebo. Ultrasonic carotid flowmetry variations are not significative excepting common carotid vasodilation under Nitrendipine. Under Nitrendipine, at J30, 5 pts show a decrease of a least 15% of the cerebral vascular resistances (responding patients); and 6 pts do not show any significative decrease of cerebral vascular resistances. For the responding pts, arteriolar vasodilation is then correlated to the decrease of BP and Dif BP, to the increase of carotid blood flow and to the arterial vasodilation; while there is no significative decrease of BP for non responding pts. It suggests an improvement of arterial compliance by a direct action on the arterial wall. Furthermore, inspite of a drop in diastolic parietal tension, there is not any group showing reflex tachycardia. Thus, antihypertensive efficacy of Nitrendipine seem to be principally subordinated to the improvement of arterial compliance.(ABSTRACT TRUNCATED AT 250 WORDS)