Vascular dementia due to multiple large strokes (multi-infarct dementia) is a well known entity. However, new clinicopathologic and neuroimaging data have highlighted the common occurrence of small vessel and microscopic vascular pathology in aging brains and recognized that vascular dementia due to small lesions is probably the most common form. In such cases, cortical microinfarcts are the strongest correlate of global cognitive function followed by basal ganglia and thalamic lacunes. Demyelination is only weekly associated with cognition and this relation is no longer significant after adjustement for the presence of lacunes. Awareness of the importance of small vascular lesions in brain aging, can improve diagnostic accuracy and help identify new targets, that could lead to novel therapeutic approaches in old age dementia.