Objective: to obtain more specific information on the morphology and pathogenesis of cerebral infarctions occurring in vertebrobasilar artery (VBA) atherosclerosis. Material and methods. Macro- and microscopic investigations of the brain, its arterial system, and heart were conducted in 69 autopsy cases with infarctions located in the vertebrobasilar system (VBS) in atherosclerosis. Results. 69 cases were found to have 206 VBA infarctions of various extent and locations. The detected infarctions were single and multiple in 27 and 42 cases, respectively. The detected infarctions included extensive (n=7), large (n=9), medium (n=63), small deep (lacunar) (n=97), and small superficial (n=30). The brain stem showed lacunar infarctions most frequently (76% of the infarctions at this site). Medium and small infarctions were identified at the same frequency in the cerebral hemispheres and cerebellum. The occurrence of 94% of the extensive and large infarctions was ascertained to be pathogenetically associated with atherothrombotic occlusion of the intracranial arteries in the VBS. 76% of the small infarctions occurred through the mechanism of cerebral vascular insufficiency in tandem atherostenosis of VBAs in conjunction with an additional decrease in cerebral blood flow under the influence of an extracerebral factor (coronary heart disease). Medium infarctions were approximately equifrequently due to the two aforementioned causes and, in some cases, to cardiogenic thromboembolism of VBAs. Infarctions were multiple in most cases; while recent large atherothrombotic infarctions were frequently concurrent with small organized infarctions resulting from tandem atherostenosis of VBAs. Conclusion. This investigation could establish the relationship between the site, extent, and pathogenetic factors of infarctions in the VBA bed in atherosclerosis, as well as the prognostic value of small infarctions as predictors for severe ischemic stroke.