Abstract <p><b>Objectives:</b> Hypertension is the one of the most significant socially sensitive diseases associated with the cerebral circulation. A persistent increase of blood pressure leads to a violation of cerebral circulation, and this fact cannot but affect the functional state of the brain innate immune cells. Therefore, the aim of the study was to analyze structural, cytochemical and functional characteristics of microglia and macrophages in the lateral ventricles of the hypertensive rat’s brain. <b>Materials and methods:</b> The material for the study was the brain of spontaneously hypertensive rats (SHR, <i>n</i> = 8) and Wistar rats (<i>n</i> = 8). Iba-1, P2Y12 and intermediate filaments protein vimentin, were used as marker proteins of microglia in comparative immunohistochemical study. <b>Results and discussion:</b> The clear presence of vimentin in the bodies of subependymal microgliocytes in both studied animal groups shows that these cells are in a preactivated state. The signs of chronic activation, which are: presence of vimentin filaments in both bodies and processes, show supraependymal and subependymal cells in SHR. This may be due to disturbances in the brain barriers under conditions of high blood pressure. It was revealed that microglia activation against the background of hypertension is not necessarily accompanied by increasing levels of phagocytic activity. Microglia of the subventricular zone has a unique morphotype, which may be due to its specific functions or structural and functional features of this forebrain area. <b>Conclusion:</b> A comparative immunohistochemical study using antibodies against Iba-1, P2Y12 and vimentin, allows us to characterize several microglia subpopulations in rats with genetically determined arterial hypertension.</p>