Heterocyclic amines or amides are provided which are useful in the enhancement of the resistance of olefin polymers to coppercatalyzed oxidative deterioration. Stabilizer compositions are also provided consisting essentially of at least one olefin polymer stabilizer and heterocyclic amines or amides; and olefin polymer compositions, such as propylene polymer compositions, containing heterocyclic amines or amides; and a process for enhancing the resistance of olefin polymers to copper-catalyzed degradation by incorporation of such compounds or of such stabilizer compositions.