The main data on issues of polymer aging caused by various factors are summarized. The characteristics of macromolecular reactions in addition to thermal, thermal-oxidative degradation, degradation caused by the aggressive environment, high-energy radiation, etc. are considered. The Study Guide is intended for students studying Master Degree Program 18.04.01 «Chemical Engineering» related to such study fields as Chemical Engineering of Polymers and Polymeric Materials as well as Chemical and Physical Modification of High Molecular Compounds, Chemical Engineering of Synthetic Rubber, Chemistry and Physics of High Molecular Compounds, Catalytic Engineering in Petroleum Chemistry and Polymer Chemistry. The Study Guide is prepared by Technology of Synthetic Rubber Department.