This paper presents the effect of gamma irradiation on polyethylene stabilized with two derivatives of carnosic acid. LDPE-stabilized samples were subjected to high energy radiation on three doses (5, 10 and 20 kGy) on the sterilization range of polymers. The stability of radiochemically degraded LDPE was achieved by oxygen uptake at 190 degrees C under isothermal and isobaric conditions. Antioxidant concentration of 0.25% w/w was selected to demonstrate the availability of these compounds for delaying oxidative degradation under hard service circumstances. The influence of substitution in antioxidant molecules on the kinetic parameters of thermal stabilization is discussed. Some mechanistic aspects in relation to the intermediates of additives are assumed.