人們在做放射診斷、治療或工業用途中會受到幅射的暴露,有些人亦會在搭飛機旅行、核子意外事故或使用電器設備中接受到幅射。游離福射穿過生物體時會產生游離而使組織的化學分子產生化學改變，進而造成生物體有害的效應。在1940年代，科學家對於內生性的硫醇化合物，例如:半腕胺酸做了一些研究，並顯示它對於游離幅射的傷害具有保護作用。之後，各種含有硫醇的合成藥物被發展出來，而且被證實極為有效。但是因為這些藥劑具有ᅳ定的毒性，所以幅射保護劑已朝向中草藥與天然抗氧化物的硏究。現在幅射保護的研究趨勢為輯射傷害的免疫調節、造血幹細胞增殖與分化等。這篇文章主要教述植物與中草藥萃取物的幅射保護潛能。

People may be exposed to ionizing radiation during diagnostic, therapeutic and industrial purposes. Some of people also get exposure to ionizing radiations during air and space travel, nuclear accidents, and use of electronic devices. Radiation may produce ions in its passage through the organisms, causing immediate chemical alterations in biological tissues and produce deleterious effects in the living organisms. Ionizing radiation induced cellular damage is implicated in carcinogenesis as well as therapy of cancer. In 1940’s a great deal of research has been carried out on endogenous thiols like cysteine showed protection against such harmful radiations. Later, various synthetic drugs containing thiols were developed and proved to be highly effective. But due to their toxicity, the research and development is more inclined towards the discovery of herbal medicines and other naturally occurring antioxidants as radiᄋprotectives. The recent trend is the use of immunomodulators to regenerate the radiation injury by development, proliferation & differentiation of the hematopoietic stem cells and progenitors. This review mainly dwells on the radioprotective potential of plant and herbal extracts