The prevalence of asymptomatic carotid bruit is 4 per cent in the general population aged over 40 years. According to most authors, it is an evident risk factor for stroke and myocardial infarction. In the present study the clinical data and Doppler flowmeter analysis of 5 groups of patients are reported. These patients had risk factors for cerebrovascular disease, without cerebral symptoms. An age matched group of healthy control subjects was also studied. The prevalence of haemodynamic stenosis (more than 50 per cent) of carotid artery is significantly higher among subjects with peripheral arteriopathy and arterial hypertension compared with other groups. On the other hand nonhaemodynamic stenosis (below 50 per cent) of carotid artery occurs to the same extent in patients and control groups. The possible implications of these findings on the knowledge of cerebrovascular obstructive disease are discussed.