Brassicaceae plants, as an important source of primary and secondary metabolites, are becoming a research model in plant science. Plants have developed different ways to ward off environmental stress factors. This is lead to the activation of various defense mechanisms resulting in a qualitative and/or quantitative change in plant metabolite production. Reactive oxygen species (ROS) is being continuously produced in cell during normal cellular processes. Under stress conditions, there are excessive production of ROS causing progressive oxidative damage and ultimately cell death. Despite their destructive activity, ROS are considered as important secondary messengers of signaling pathway that control metabolic fluxes and a variety of cellular processes. Plant response to environmental stress depends on the delicate equilibrium between ROS production, and their scavenging. This balance of ROS level is required for performing its dual role of acting as a defensive molecule in signaling pathway or a destructive molecule. Efficient scavenging of ROS produced during various environmental stresses requires the action of several non-enzymatic as well as enzymatic antioxidants present in the tissues. In this review, we describe the ROS production and its turnover and the role of ROS as messenger molecules as well as inducers of oxidative damage in Brassicaceae plants. Further, the antioxidant defense mechanisms comprising of enzymatic and non-enzymatic antioxidants have been discussed. Keywords: Abiotic stress, Antioxidant defence, Brassicaceae, Oxidative stress, ROS