This book represents current findings on the impact of oxidative stress in the pathogenesis of diseases and underlying mechanisms of antioxidants influencing health and disease processes. The book is divided into seven sections that describe how antioxidants defend oxidative stress-mediated diseases as well as recent developments, future opportunities, and challenges. Sections 1 analyses the role of oxidative stress in aging and associated diseases as well as the use of antioxidants in health maintenance, preventing and repairing injuries caused by oxidative stress. Section 2 represents the status of various antioxidants in cigarette smoking and antioxidant defense against exercise-induced oxidative stress. Section 3 focuses on the effect of oxidative stress in the pathogenesis of neurodegeneration and the existing status of antioxidant therapy. Section 4 covers the impact of oxidative stress at different levels of chronic degenerative diseases, as well as treatment with antioxidants to revert and diminish the cellular injury. Section 5 offers the importance of antioxidants in abating the pathological processes involved in hypertension and stroke. Section 6 presents the complexity associated with oxidative stress and metabolic disorders as well as the potential of antioxidants used in amelioration of related pathologies. Section 7 discusses the antioxidant defense against oxidative stress-mediated erectile dysfunctions and the significance of antioxidants in pregnancy. The book represents the copious set of specific research updates and diaphanous understanding of oxidative stress-mediated cellular damages and role of antioxidants in disease processes from experienced and eminent academicians, researchers, and scientists from throughout the world. Suitable for professionals, academicians, students, researchers, scientists and industrialists around the world in the biomedical, health, and life science fields.