The aim of this study was to evaluate the prevalence of atherosclerotic carotid lesions in arterial hypertension by 2D echo-color Doppler and the effect of night-time pressure fall by ambulatory blood pressure monitoring. One hundred and eighty-two subjects were studied: 60 normotensive control subjects, 60 mild-moderate essential hypertensives and 62 isolated systolic hypertensives. Hypertensive subjects were divided into two groups on the basis of night-time pressure fall (Group 1 > 10% and Group 2 < 10%). Thickness > or = 0.95 mm was considered a sign of intima-media thickening, and the plaque as a focal thickening of > or = 2 mm, based on echogenic characteristics (hard, fibrous, mixed, soft and haemorrhagic) and site (common carotid, bifurcation, internal and external carotid). Compared to normotensives, mild-moderate essential hypertensives, much more frequently, showed a pattern of intima-media thickening (p = 0.025) with one or more plaques (p = 0.0025), while normal carotid arteries (p = 0.0002) were less frequent. In isolated systolic hypertensives the prevalence of vasal lesions was not significantly different from that observed in mild-moderate hypertensives. In Group 2 of mild-moderate hypertensive subjects, carotids with one or more plaques (p = 0.02) were significantly more frequent compared to Group 1, while normal carotids (p = 0.04) were less frequent. Plaques were more often localized at the level of the common carotid artery and at the bifurcation and less frequently at the level of the internal and external carotid arteries; more often the lesions were hard, less fibrous, mixed and soft.(ABSTRACT TRUNCATED AT 250 WORDS)