Objective. To evaluate the role of lipoprotein (a) in an atherosclerotic lesion of precerebral arteries and stroke development. Material and methods. Thirty-eight patients with atherosclerotic lesions of the carotid arteries established by duplex scanning, including 28 post stroke patients and 10 patients with asymptomatic atherosclerosis, were examined. Lipoprotein (a) was determined by immunosorbent assay in the serum and supernatant after 3-day cultivation of neutrophils. Results and conclusion. There was a correlation between serum lipoprotein (a) and endothelium-dependent vasodilation of the brachial artery, and the relationship of culture lipoprotein (a) with the severity of atherosclerotic lesions of precerebral arteries and prothrombin time. Thus, the effect of lipoprotein (a) on the atherogenesis may be mediated by endothelial dysfunction and the mechanism of realization of stroke development is prothrombogenic effects on hemostasis.