Microglia, one of the glial cell types in the CNS, is an important integral component of neuro-glial cell network. They have been observed in the brain parenchyma from the early stage of development to the mature state. Microglia act as brain macrophages when programmed cell death occurs during brain development or when the CNS is injured or pathologically damaged. Microglia can be considered as the main cell in brain immune surveillance, can present antigens in the molecular context of MHC class II expression to CD-4 positive T cells, are capable of Fc-mediated phagocytosis, and share many common antigens with hemopoietic and tissue macrophages. Furthermore, there is accumulating evidence that microglia are involved in a variety of physiological and pathological processes in the brain by interacting with neurons and other glial cells and through production of biologically active substances such as growth factors, cytokines, and other factors. HM are isolated from human brain tissue. After purification, HM are cryopreserved and delivered frozen. Each vial contains >1 x 10^6 cells in 1 ml volume. HM are characterized by immunofluorescent method with antibody to OX-42 (CD 11b/c). HM are negative for HIV-1, HBV, HCV, mycoplasma, bacteria, yeast and fungi. HM are ready to plate in a culture vessel for experiment. HM are not recommended for long term culture since microglia do not proliferate in regular culture.