Oxidative stress plays a crucial role in the pathophysiology of various diseases when there is a disruption of the intracellular redox balance and the homeostatic balance between cellular oxidants and antioxidants. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) react with molecular targets including proteins, lipids, and nucleic acids contributing to mitochondrial injury and cellular dysfunction. This book intends to provide the readers with an extensive overview of the novel approaches and prospects based on oxidative and nitrosative stress in the pathophysiology of various diseases and in the current treatment strategies with antioxidants.