[en] Cryo preservation of cells, tissues or organisms (i.e. the storage at liquid-nitrogen or nitrogen vapour temperature) offers the most secure form of preservation, allowing cells to be maintained unaltered for a long time and preventing them from ageing. On the other hand, the multi-year exposure of cryo-preserved cells (like: stem and germ cells) to the environmental γ-ray background might induce a radiation-damage accumulation, due to the inhibition of cellular repair mechanisms, and contribute to cancer or non-cancer pathology risk assessment when such cells should be transplanted in individuals. To investigate the effect of the cryo preservation on the cell response to radiation exposures, the response of different biological systems (bacteria and mammalian cells) to γ-rays has been evaluated after irradiation in cryo-preserved and culture conditions, as a function of dose and dose rate, in terms of a variety of cellular and molecular end-points.