While radiation has therapeutic uses, too much radiation is damaging to cells. The most important acute side effect of radiation poisoning is damage to the bone marrow. The bone marrow produces all the normal blood cells, and therefore a high dose of radiation can lead to low blood counts of red cells, platelets and white blood cells. Humans that receive a lethal dose of radiation as in the setting of an accidental exposure die of bone marrow failure. While there are a few drugs that will decrease toxicity when given before exposure to radiation (“radioprotectants”); currently, no effective therapy exists to mitigate bone marrow toxicity of radiation when given after radiation exposure (“radiomitigants”). The identification of successful human radiomitigants is a top research priority of the US Department of Homeland Security and National Institutes of Health.