The carotid sinus is a dilatation of the common carotid artery at the point of its division into the internal and external branches. It usually involves and may be restricted to the proximal part of the internal carotid artery (1), customarily being found at the level of the upper margin of the thyroid cartilage. Since the point of division of the common carotid artery is variable, however, the sinus may be located, exceptionally, as high as the level of the hyoid bone or at the lower border of the cricoid cartilage. Since atheromatous deposits tend to occur at points of dilatation, narrowing, branching, or turning of blood vessels, they can be expected in the walls of the carotid sinus. In recent years, several observers have noted the frequency of significant occlusive disease in the extracranial vessels, especially in this sinus (2–4). Autopsy examination, also, shows that extracranial cerebral arterial calcification occurs predominantly in the carotid sinus (5). The amount of calcium in the sinus wall bears no relation to the actual size of the atheromatous deposits or to the degree of encroachment on the lumen. Thus, densely calcified walls of the sinus, as observed at autopsy or on roentgenograms, may be present with little or no narrowing of the lumen, and completely occluded carotid sinuses may exist with no calcium deposition in their walls. No clinical correlation need be expected, therefore, between the degree of calcification and the degree of stenosis. Significantly too, severe grades of occlusive disease in the carotid sinuses may be found with little impairment of cerebral function where adequate collateral circulation through the remaining extracranial supply exists. Carotid sinus calcification has characteristic appearances and location on roentgenograms of or including the cervical area (Fig. 1). A rounded eggshell formation with open upper and lower margins is found at the level of the thyroid cartilage. Variations from frank ectasia with densely calcified walls (Fig. 2) to small linear plaques of calcium are commonly seen. Calcified lymph nodes differ in appearance since they customarily have a dense core of calcium in their centers and several nodes, often in a chain, may be involved. Calcified thyroid adenomata usually occur at a lower level than the thyroid cartilage, and though the calcification may be of eggshell type, the upper and lower ends are not open as in typical carotid sinus calcification. Calcium deposits are commonly observed in the carotid sinus on the chest or cervical spine roentgenograms of patients over fifty years of age. In a series of 70 cervical spine examinations (28 males, 42 females) and in another series of 200 chest radiographs (100 males, 100 females) where the cervical area was included, carotid sinus calcification was found in 18 per cent of all subjects over fifty.