The thermal degradation (TG) of poly(vinyl acetate) irradiated with gamma-rays has been investigated by dynamic thermogravimetry in a nitrogen atmosphere. The overall effect of irradiation is to render poly(vinyl acetate) more susceptible to thermal degradation. The change in activation energy of thermal degradation with dose showed a behaviour parallel to the change of intrinsic viscosity with dose. The maximum E(a) values were found to correspond with the maximum observed on [eta] versus dose curves. This behaviour indicates a relationship between the thermal stability and molecular size.