Animal models of neuroinflammatory processes are needed to study the involvement of inflammation in neurodegenerative disorders such as Parkinson's and Alzheimer's diseases. One of the models used is based on lipopolysaccharide (LPS) as brain inflammation-inducing agent. This toxin is a potent inducer of inflammation and has different effects on cells of the immune system, as microglial cells. This chapter describes a protocol for the model of brain inflammation in rats based on the unilateral stereotaxic injection of LPS, which mimics the inflammatory milieu produced in some brain diseases.