It is reviewed the achievements in the field of radiation-genetics investigations of low doze radiation influence on life span. It is suggested that life span decreasing after irradiation is due to stress-induced premature cell senescence. Life span increasing after irradiation, possibly, is connected with stress-induced activation of FOXO transcription factors, which induce on the basis of stress depth: 1) genes of stress tolerance (MnSOD, catalase, GADD45, p27), 2) apoptosis genes (Bim, FasL). Stress-resistance as well as apoptosis of damaged cells can attenuate aging. In generations of chronic irradiation life span increasing may be due to inbreeding depression removal in populations of laboratory animals.