Oxidative stress is defined as a non balanced redox condition where prooxidants overpower the antioxidant potential what can result in series of pathophysiological disorders followed by an infection or tissue damage. Microglial cells, as residual macrophages of the brain, have the function to monitor neural tissue health. They are activated in a case of hypoxia, like a stroke, when they express different parameters, including iNOS enzyme which is an indicator of oxidative stress. Celastrol, an extract of the plant Tripterygium wilfordii, is a member of pentacyclic triterpenes. It has been efficiently used in the traditional medicine to treat autoimmune diseases, asthma, chronic infections and neurodegenerative deseases owing to its antioxidative and anti-inflammatory characteristic. The purpose of this research was to perceive if celastrol, as a potential antioxidative agent, can prevent microglial cells activation and this way also prevent the oxidative stress growth in the case of hypoxia. The results indicate the number of microglial cells treated with celastrol have, in regard to controle group, reduced and there is an after effect - a reduced induction of the iNOS enzymes. We can conclude that celastrol has revealed it self as a successful inhibitor of microglial cells activaton, which also contributed oxidative stress reduction, and it can also beused as a potential antioxidative resort invarious deseases treatments.