Radiopharmaceutical agents are utilized for imaging and treatment in nuclear medicine. Ionizing radiation produces free radicals in the cell that can induce damage to the DNA and lead to side-effects and/or secondary tumors. Radioprotective agents are useful in eliminating or reducing the severity of deleterious cellular effects, which are caused by exposure to internal and/or external irradiation in patients or staff personnel. There are two strategies for the potential use of radioprotective agents in patients, including agents used in patients for selective protective effects, such as reducing mocusitis, myelotoxicity, and kidney damage induced by ionizing radiation in radioiodine and radiolabeled peptide therapy. Second, radioprotective agents can reduce chromosomal aberration induced by gamma- or beta-rays and reduce the risk of tumors in personnel and patients.