The book gives the methods for the synthesis and biological activities of chalcones and their modifications to various different sized heterocycles like flavonoids flavanone aurones pyrazoles oxazoles benzothiazepines pyrimidines etc. This book also highlights anticancerantifungal antibacterial antiHIV anti-inflammatory and antioxidant potential of chalcones and their derivatives. The structure activity relationship of different chalcones and their derivatives is also discussed in the the present book which determine their ability to inhibit the growth of microorganisms and evaluate the toxicological effects on surrounding life.