Viral vectors represent an efficient tool for introducing genetic material into cells and their application plays an important role in various therapies and neuroscientific research. Different methods can be used to introduce the viral vector into the central nervous system, and one of them is direct stereotaxic injection. Since microglia are considered the main supervisors in the brain and participate in the inflammatory response activation, the aim of this work was to examine whether the stereotaxic injection of a lentiviral vector causes the activation of an inflammatory response (i.e. microglia), change in the microglia morphology and change in the expression of TLR2, a receptor activated in case of infection. The immunohistochemical staining method was performed 7 and 14 days post injection on thin sections of mice brains in order to visualize the microglia marker (Iba-1) and TLR2. The inflammatory response is localized in the injection site, is transient, accompanied by a change in the microglia morphology and significantly lower 14 days post injection in comparison to 7 days post injection. In the injection site, an increased TLR2 expression was also recorded 7 days post injection, while 14 days post injection it was significanly lower. This research established that the activation of inflammatory response in the brain is not caused by the lentiviral vector, but the introduction method (stereotaxic injection). Moreover, this research confirmed that lentiviral vectors represent a safe tool for introducing genetic material into the mouse brain.