Patients with atherosclerosis in the carotid arteries are at risk of ischemic stroke and cognitive decline due to emboli and chronic hypoperfusion of brain tissue. Revascularization procedures improve cerebral hemodynamics, which has some effect on cognitive function. Some authors suggest that the presence of stenosis in the carotid arteries is an independent factor influencing cognitive decline. The aim of this study was to investigate the relationship between the degree of stenosis of a stented carotid artery and attentional performance in individuals with carotid atherosclerosis. A prospective longitudinal study was conducted at a single center involving patients during cardiology hospitalization (T-1) and 1 year after hospital admission (T-2) for invasive treatment of carotid stenosis. The attention D2 test by R. Brickenkamp was used. The study showed that a critical degree of internal carotid artery stenosis is associated with poorer attentional performance in individuals undergoing carotid artery stenting. However, the ability to concentrate improved one year after the procedure in all groups of patients who underwent carotid artery stenting, regardless of the degree of internal carotid artery stenosis. It was also found that the side of the vasoconstriction (right/left) in patients with atherosclerosis in the carotid arteries has no influence on cognitive functions in relation to attention.