The book entitled, An Introduction to Drug Design aims to optimize the discovery of drugs at a low cost and on occasions to change their pharmacokinetic and pharmacodyanamic properties. The introductory chapter which forms the basis of drug discovery is followed by the present-day thinking regarding the best approaches to drug discovery are considered. Similarly, there have been major advances in the employment of computers in structure-activity analysis, and a discussion of the state of the art in this area is also included. The chapter on QSAR highlights the role of physico-chemical parameters in predicting the future course of drug discovery with rational drug design. The role of enzymes in drug action is well established, and a chapter on design of enzyme inhibitors is well documented. In addition, the increased understanding of the design and utilisation of prodrugs has led to a discussion of the relevant issues in this text. Thus the book will fill the need of a text for designing new drugs and the principles of new drug discovery.