Most ionizing radiation-induced damage is caused by radical oxygen species (ROS). Some radioprotectors, such as amifostine, exert radioprotective effects by scavenging radical oxygen species. Recent studies show that hydrogen (H2) has antioxidant activities that protect the brain and intestine against ischaemia-reperfusion injury and stroke by selectively reducing hydroxyl and peroxynitrite radicals. However, it is seldom regarded as a radioprotective agent. In like manner, we hypothesize that hydrogen may be an effective, specific and novel radioprotective agent. But H2 is explosive, while hydrogen-rich solution (solution such as physiological saline saturated with molecular hydrogen) is safer.