Enzyme inhibitors play a pivotal role in pharmaceutical and nutraceutical industries. The primary understanding of the action of inhibitors helps pharmacologists during the design process for developing new therapeutic drugs. Most drugs treat various chronic and life threatening diseases owing to their specificity and the potency of enzymes which they can inhibit. Enzyme inhibitors are used to screen various levels of diseases which propel the growth of inhibitors. The potential for enzyme inhibitors in the therapeutics market is very high as the biochemical properties and classes of enzyme inhibiting products are readily available. The other broad aspect of enzyme inhibition is their application in analytical sensors. These sensors assist in monitoring various environmental factors. Understanding the mechanism of inhibition and regeneration of enzymes is a general problem of great importance for many biochemists and biotechnologists especially when using immobilized enzymes. This reference compiles applied information about enzyme inhibitors used in medicine and environmental monitoring applications. Chapters presented in this volume cover special topics including biosensors, crop improvements in agriculture, biofuel production, pesticide and heavy metal detection, and drug therapy for human diseases such as breast cancer, neurological diseases and viral infections. The collection of topics in this volume makes it an informative resource for readers at all academic levels on the applications of enzyme inhibitors in medicine and environmental sciences.