Evaluation of lifelong health risks from ionizing radiation, especially from low-dose radiation, needs comprehensive understanding of radiation response at multi-cellular levels. Recent studies have shown both direct and indirect interactions between individual exposed and unexposed cells, which might affect manifestation of various late effects caused by low-dose ionizing radiation. Integration of such multi-factorial interactions can not be accomplished by currently available methods but requires new approaches such as “Systems Radiation Biology”. In this symposium, present status of systems radiation biology research is presented by three investigators, and its possible future will be discussed.