Book excerpt: Fluorine chemistry is an expanding area of research that is attracting international interest, due to the impact of fluorine in drug discovery and in clinical and molecular imaging (e.g. PET, MRI). Many researchers and academics are entering this area of research, while scientists in industrial and clinical environments are also indirectly exposed to fluorine chemistry through the use of fluorinated compounds for imaging. This book provides an overview of the impact that fluorine has made in the life sciences. In the first section, the emphasis is on how fluorine substitution of amino acids, peptides, nucleobases and carbohydrates can provide invaluable information at a molecular level. The following chapters provide answers to the key questions posed on the importance of fluorine in drug discovery and clinical applications. For examples, the reader will discover how fluorine has found its place as a key element improving drug efficacy, with reference to some of the best-selling drugs on the market. Finally, a thorough review on the design, synthesis and use of 18F-radiotracers for positron emission tomography is provided, and this is complemented with a discussion on how 19F NMR has advanced molecular and clinical imaging.