Irradiated egg shells exhibit a paramagnetic center at g = 2.0018. The center is stable up to temperatures of 150°C and against u.v. light. The center concentration as determined by electron paramagnetic resonance spectroscopy increases with absorbed dose. A dose range between 3 Gy-10 kGy was examined in which egg shells can serve as a dosimeter. Precision of measurement was found to be better than ± 10% on a 95% confidence level, for absorbed doses above 10 Gy. Egg shells are shown to be applicable for retrospective dosimetry after radiation accidents. | Irradiated egg shells exhibit a paramagnetic center at g = 2.0018. The center is stable up to temperatures of 150°C and against u.v. light. The center concentration as determined by electron paramagnetic resonance spectroscopy increases with absorbed dose. A dose range between 3 Gy-10 kGy was examined in which egg shells can serve as a dosimeter. Precision of measurement was found to be better than ±10% on a 95% confidence level, for absorbed doses above 10 Gy. Egg shells are shown to be applicable for retrospective dosimetry after radiation accidents.