The change in radiation sensitivity with temperature is quantitatively the same for biological macromolecules and synthetic polymers. The mechanisms for this effect are due to secondary processes occuring after the primary ionization and are associated with the presence of free radicals. The activation energy associated with the temperature dependence has been calculated for various biological macromolecules and synthetic polymers, the Arrhenius plot being adopted as the conventional format for data presentation. In all cases the curves were complex. -- AATA