Matrix metalloproteinases (MMPs) are proteolytic enzymes that are involved in many physiological and pathological processes. The field of MMP research is very important due to the implications of the distinct paralogs in both human physiology and pathology. Over-activation of these enzymes results in tissue degradation, producing a wide array of disease processes such as rheumatoid arthritis, osteoarthritis, tumor growth and metastasis, multiple sclerosis, congestive heart failure, and others. Thus MMP inhibitors are candidates for therapeutic agents to combat a number of diseases. The present book discusses the design and development of different classes of inhibitors of important classes of MMPs, such as gelatinases and collagenases. The articles focus specifically on structure-activity relationships of all classes of compounds and on their modes of action and specificity of binding with the receptors based on experimental and theoretical studies. These studies constitute a valuable asset for all those involved in drug development.