The manual is devoted to one of the most important sections of radiation biophysics, the urgent problem of chemical protection against radiation damage. It was based on materials from a lecture course given by the authors to neither the Department of Biophysics of the Biological Faculty of Moscow State University. Primary processes of radiation damage and their modification with the help of chemical protection means are considered. The material on chemical protection includes issues of assessing the radioprotective effectiveness of chemical protection means (radioprotectants).