This is an introductory text intended to give the non-specialist a comprehensive insight into the science of biotransformations. The book traces the history of biotransformations, clearly spells out the pros and cons of conducting enzyme-mediated versus whole-cell bioconversions, and gives a variety of examples wherein the bio-reaction is a key element in a reaction sequence leading from cheap starting materials to valuable end-products (such as pharmaceuticals and agrochemicals, fragrances and flavours). Biotransformations involving the hydrolysis of esters, amides and nitriles, the synthesis of esters and amides, reduction and oxidation reactions and carbon-carbon bond-forming systems are discussed. The book finishes with a discussion of some industrially important large-scale bioconversions.