Abstract: Radioprotectors are designed to disrupt the progress of damage caused by radiation in normal tissues and to promote the recovery of the damaged tissues. This article review the function of the following agents as radioprotectors and their mechanism of action: sulfhydryl compounds, natural antioxidants, nitroxides, and angiotensin-converting enzyme inhibitors. Prospective functions of these agents were also discussed. This article hope to provide researchers with insights into radioprotector research.