The inhibition of thermal- and irradiation-oxidation of LDPE in the presence of a number of phenols was studied using the chemiluminescence method. 1-pyrenol and various phenanthrol isomers were compared with a number of commercially available phenolic antioxidants. The following order of efficiency was found: Irganox 1330 ≥ 1-pyrenol > Sumilizer MDP-S > 4-phenanthrol > 1-phenanthrol > 3-phenanthrol > Sumilizer GM-S > 2-phenanthrol > Sumilizer GS > 8-quinolinol > Sumilizer BHT. The antirad effect of the studied anti-oxidants in LDPE follows, up to 10 Mrad, the same efficiency order as in the thermal oxidation.