Oxidative stress has become a real health problem very common in our modern life. A large number of diseases, the most widespread of the contemporary era, such as hypertension, diabetes, cardiovascular diseases, neurodegenerative pathologies, cancers, have been explained in part as a consequence of oxidative stress. The knowledge of the biological and pathological roles of free radicals is recent and in full evolution. These molecules are unstable compounds with extremely short lifetimes and are therefore difficult to identify and quantify. This course focuses on the study of the molecular mechanisms of free radical production as well as their physiopathological roles and the defense systems against these radical molecules. Currently, these metabolites are considered as major participants in all biochemical reactions and many pathological processes. This course will therefore provide the theoretical skills necessary for experimental training