AbstractThis chapter focuses on the effect of radiation on biological systems, particularly on radiation-induced damage to DNA, lipid and protein. The characteristics of Nigella sativa that make it useful against radiation damage are described, as well as its phytochemical profile, and pharmacological and radioprotective properties. The antioxidant properties and detoxification of reactive oxygen species of thymoquinone, the main active constituent of the volatile oil of Nigella sativa seeds, are highlighted.