Abstract: Non-targeted and delayed effects are relative phenomena in cellular responses to ionizing radiation.These effects (bystander effects, genomic instability and adaptive responses) have been studied most extensively for radiation exposures. It is clear that adaptive responses, bystander effects and genomic instability will play an important role in the low dose-response to radiation. This review will provide a synthesis of the known, and proposed interrelationships amongst low-dose cellular responses to radiation. It also will examine the potential biological significance of non-targeted and delayed effects of exposure to ionizing radiation.