Ebselen is a low toxicity selenium heterocycle very studied for its antiinflammatory and antioxidant activity. In this context, ebselen is capable to mimic the glutathione peroxidase (GPx) catalytic activity, which is very important to protect cellular components from damage caused by the accumulation of reactive oxygen species (ROS). Although there are many studies on this compound, there are still divergences on its mechanism of action as GPx mimetic. In this manuscript is present a review of the last 10 years regarding the studies of ebselen mechanisms of action as antioxidant as well as some of its biological application and of its derivatives.