This book which is edited by eminent scientist Satya P. Gupta, covers the most recent development on design and discovery of the most useful drugs acting against several life threatening diseases such as cancer, viral infections and many others in two volumes. All of these drugs are based on inhibitions of various enzymes. Most human diseases are found to be associated with the overexpression of the enzymes. The book presents the structural aspects of various enzymes, their active sites, and the structural requirements of chemicals for strong interactions with enzymes. Volume One contains twelve chapters related to enzyme inhibitors acting as anticancer and antiviral drugs (each written by highly acclaimed authors), and Volume Two contains ten chapters on enzyme inhibitors acting against miscellaneous diseases written by equally competent authors. The book may be an asset for drug industries, research organisations, and individual researchers.