Pericytes are contractile smooth muscle-like cells that cover the abluminal surface of microvessels. They are most abundant on venules and are common on capillaries. The pericyte population is highly variable between different tissues and organs and appears to show functional heterogeneity. Human brain vascular pericytes play a crucial role in the formation and functionality of the blood-brain barrier; but also in the regulation of angiogenesis, survival of endothelial cells, and clearance and phagocytosis of cellular debris. Due to the close relationship with endothelial cell structure and blood flow, an excess or deficiency in vascular pericyte activity is related with in various pathological conditions including hypertension, diabetic retinopathy, Alzheimer’s disease, multiple sclerosis, and central nervous system tumor formation.