Glut 5 is a member of a family of facilitative glucose transporter proteins that are involved in the transportation of glucose and/or fructose across plasma membranes. Glut 5 is one of three isoforms expressed in brain. Using immunocytochemical and immunoblotting techniques in formalin fixed tissue, we have shown that Glut 5 is exclusively expressed in microglial cells of the human and rat brain. Our data demonstrate that unlike other microglial markers, Glut 5 can be used as a microglial marker in formalin fixed tissue.