One hundred and ninety-five consecutive referrals to the vascular laboratory for carotid artery investigation have been studied. Carotid bruits were assessed by the referring clinician and documented. All patients underwent bilateral imaging and spectrum analysis of the extra-cranial carotid vessels using a pulsed Doppler ultrasound technique. Eighty-two were further assessed by X-ray contrast angiography. Of 390 internal carotids examined by ultrasound, 65 exhibited intraluminal turbulence of which 49 (75 per cent) had a bruit. In 62 (56 per cent) of 111 internal carotids in the series which were said to have a bruit on clinical examination, no turbulence was found; in 15 instances the external carotid vessel was shown as the true source of turbulence and in the remainder the bruits may have been transmitted from the heart. One hundred and fifty-six vessels were assessed by X-ray and 55 shown to have significant stenosis; 38 (69 per cent) of these exhibited a bruit. Bruit was often absent at high degrees of stenosis and in occluded vessels. Although a carotid bruit is often a marker of internal carotid intraluminal turbulence and stenosis, this is by no means always so. Cervical bruit may also be due to a diseased external carotid or to sounds transmitted from a more proximal source. Conversely, absence of bruit is a feature not only of normal vessels but of many arteries which are stenosed (especially if this is of high degree) or occluded.