Abstract: Polymer bound antioxidants are provided in which the antioxidant stabilizer groups are chemically bound to polymers or copolymers by an acylaminoimide or diacylhydrazide function. The polymer bound antioxidants are prepared by reacting hydrazido substituted antioxidants with some or all of the anhydride groups of anhydride containing polymers or copolymers. The concentration of the stabilizers bound to the polymer may be readily varied depending upon the particular end-use of said polymer. Polymer with high concentrations of bound antioxidants can be used as masterbatches to stabilize other polymer systems.