This book discusses both the beneficial and harmful aspects of NO in biology and medicine, and also introduces the emerging discovery of artemisinin in antitumor, antibacterial infection, anti-inflammation, and antiaging contexts. In 1992 nitric oxide (NO) was voted “Molecule of the Year” by Science magazine, and the discovery of its physiological roles has led to Nobel Prize-winning work in neuroscience, physiology and immunology. The book explains why we should maintain a steady-state NO level that is derived from neuronal or epithelial NO synthase, and avoid the extremely high NO level resulting from inducible NO synthase. The book offers a valuable resource for medical chemists, clinicians, biologists and all those interested in health and disease.