Assessment of remote genetic risks of chronic exposure to ionizing radiation should contain information about the spontaneous levels of genetic end-points, doubling doses and time-course of these end-points in chronically irradiated, randomly mating populations of model species. In our previous studies, we have described the time-course of different end-points (chromosome aberrations, embryonic lethality and abnormal sperm heads) in natural populations of a model mouse-like species, the bank vole, living in radiocontaminated areas over 22 animal generations within 10 years following the Chernobyl accident. The results of further studies showed that there are signs of multiple processes occurring simultaneously in chronically irradiated populations: (i) the “direct” response of each investigated animal to its individual irradiation, (ii) the transgenerational transmission and accumulation of radiation-induced damages, and (iii) development of radioadaptive effects. These data are congruent with population genetic theories, namely, the equilibrium theory postulated about balance between the accumulated mutation load and elimination of mutations through natural selection in large, randomly mating populations. This paper briefly summarises the results obtained by our research team, as well as literature data on the time-course of genetic effects, which can be regarded as a part of microevolutionary processes occurring in natural populations of model mouse-like species inhabiting areas with radiation contamination. The possible influence of the observed multigenerational processes (transgenerational accumulation of radiation-induced damages and development of radioadaptive effects) on dose response and risk assessment in the remote generations under chronic exposure to ionizing radiation is also discussed.