Chicken, duck, and quail egg shells were gamma-irradiated and investigated by electron paramagnetic resonance (EPR) at ambient temperature and at 113 K. The EPR-active species after gamma-irradiation were attributed to the CO3-, CO33-, and CO2- radicals at ambient temperature and at 113 K. Furthermore, when the samples were stored in an even at 423 K for about I It new EPR signals appeared at ambient temperature in addition to the above ones and these signals were attributed to the (CH3)(2)C-R radical. These signals appear also at 113 K, but they are broadened likely due to the freezing of some of their motions. Any significant difference between the egg shells of poultry and those of village-grown chickens could not be observed in EPR spectra. The duck and quail egg shells exhibit the same signals and therefore indicate the inducement of the same radicals. The spectroscopic splitting and the hyperfine interaction values were found to be consistent with the literature data.