To decrease the intracellular oxidative stresses which are caused by reactive oxygen species (ROS) including superoxide radicals, hydroxyl radicals, singlet oxygen, and hydrogen peroxide, the topic of free radical and antioxidant is broadly discussed in the biologic and medical fields to date. However, the extracts from indigenous plants in Taiwan have rarely been applied on antioxidant in the literature. In this article, therefore, oxygen toxicity, the sources of intracellular ROS, and the intracellular antioxidant defenses as well as the potential antioxidant activity of extracts from indigenous wood in Taiwan are addressed.