Based on a conference on Oxidative Stress and Redox Regulation, held at the Pasteur Institute, Paris, this work examines fundamental, chemical, biological and medical studies of free radicals on different targets and the consequences of their reactivity. It covers the chemistry and biochemistry of free radicals, free radicals as second messengers that group the activation of transcription factors and enzymes, the importance of the antioxidant system in cell metabolism regulation, and the role of free radicals and antioxidants in disease management. The editors of this work are three of the most respected pioneers in the field. Dr. Montagnier is credited as the discoverer of HIV.