Heterocyclic chemistry comprises at least half of all organic chemistry research worldwide. In particular, the vast majority of organic work done in the pharmaceutical and agrochemical industries is heterocyclic chemistry. The fifth edition of Heterocyclic Chemistry maintains the principal objective of earlier editions – to teach the fundamentals of heterocyclic reactivity and synthesis in a way that is understandable to second- and third-year undergraduate chemistry students. The inclusion of more advanced and current material also makes the book a valuable reference text for postgraduate taught courses, postgraduate researchers, and chemists at all levels working with heterocyclic compounds in industry. Essential teaching material in the early chapters is followed by short chapters throughout the text which capture the essence of heterocyclic reactivity in concise resumés suitable as introductions or summaries, for example for examination preparation. Detailed, systematic discussions cover the reactivity and synthesis of all the important heterocyclic systems. Original references and references to reviews are given throughout the text, vital for postgraduate teaching and for research scientists. Problems, divided into straightforward revision exercises, and more challenging questions (with solutions available online), help the reader to understand and apply the principles of heterocyclic reactivity and synthesis.