Licorice, known as "sweet root," is an herbal drug, which has long been used as a demulcent and elixir in Chinese medicine. It is used as an assistant drug to harmonize and to enhance the activity of other ingredients, reduce toxicity, as well as improve flavor. The multiple biological activities include, detoxification, anti-ulcer, anti-inflammation, anti-atherogenic, anti-tumor, anti-viral, anti-carcinogenic,neuroprotective, hepatoprotective,and radiation protective activities. This monograph documents the old and recent explosive growth of the knowledge of the mechanisms of action and entirely new biological effects of the major active components of licorice. The safety, low cost, and already proven efficacy of this age old natural medicine makes it a promising agent for the treatment of an old-age disease like cancer and other human diseases.Thus, this monograph should help shed some light on this new and exciting field of research and should be especially useful to clinicians, health providers, basic researchers, and pharmaceutists, or anyone else who may be of interest considering utilizing this monograph to understand the new and emerging applications in medicine.