Despite years of research world-over, non-toxic and effective radiomodulators remain elusive. In recent years, there has been a shift towards the use of herbals, which are also apparently being viewed as sources of promising radiomodulatory drugs. This book discusses the potential of radiation countermeasure agents and radiosensitizers of herbal origin, their multifaceted mode of action, specifically the use of the former in a nuclear theatre of operations, rescue operations and deep space missions in addition to their application during radiotherapy.