The total synthesis of structurally complex natural products has challenged and inspired generations of chemists. However, despite their history as privileged bioactivity-rich scaffolds, the use of natural products in drug discovery has waned.Recent developments in biocatalysis have resulted in the application of enzymes for the construction of complex molecules. This dynamically developing field is increasingly becoming a competitive alternative for classical total synthesis. Giving readers an in-depth overview of the current state of the field, this book will be of wide interest to natural products and drug researchers with a chemical or biochemical background and biocatalysis experts in academia and industry.Chapters include emerging enzymes from biosynthetic pathways, enzymes for building block synthesis and late-stage derivatisation as well as the formation of specific structural elements, such as chiral amines and heterocycles. Other important aspects for the efficient chemoenzymatic synthesis of bioactive molecules include the development of multi-enzyme cascades, engineered enzymes and strategic considerations for the use of biocatalysts in the synthesis of natural products and synthetic drugs.