This chapter describes the relationships between oxidative stress and the metabolic syndrome. Evidence suggests that oxidative stress may be involved in the aetiology, pathogenesis, and development of the metabolic syndrome. Additionally an important question remains to be asked: should we focus on antioxidant supplementation for managing the progression of complications, or on earlier steps before the development of complications? We think that it is crucial to interfere in both steps to prevent and treat several diseases, including the metabolic syndrome. Furthermore, antioxidant therapy may not only be too late, but it may also miss a large fraction of the target, as nonoxidative pathways do also contribute to cell damage.