Lacunar stroke occupies a special place among the various subtypes of ischemic stroke, accounting for about 25% in its structure and pathogenetically most often associated with cerebral microangiopathy caused by arterial hypertension (AH) and stenotic tandem atherosclerosis (AS) of cerebral arteries. Small deep (lacunar) infarction (SDI) of the brain is its structural basis. In recent years, understanding of its heterogeneous pathogenesis, clinical and practical significance was significantly expanded in connection with the widespread introduction into practice of highly informative neuroimaging methods (first of all, the newest MRI methods), which make it possible to identify SDI of the brain at various stages of their development, including in the acute period of lacunar stroke. This review covers in the historical aspect the issues of morphology, pathogenesis, clinical and neuroimaging dynamics of hypertensive and atherosclerotic SDI, including the criteria for their differential diagnosis. Particular attention is paid to the problems of asymptomatic ('silent') SDI, which, according to recent research, along with the diffuse pathology of the cerebral white matter, make a large contribution to the development of cognitive impairment up to the development of vascular dementia, and also are predictors of severe hemorrhagic and ischemic stroke in patients with AH and AS.