Lipids are an integral part of cell membrane architecture, are intermediaries in cell metabolism, and are involved in transmitting cell signals from hormones, growth factors and nutrients. A number of lipases and phospholipases, lipid kinases, lipid phosphatases, sphingosine kinases, and their reaction products have been implicated in fundamental cellular processes including cell proliferation, division and migration. These enzymes and their products underlie the molecular mechanisms of numerous human diseases, in particular metabolic disease (diabetes), cancer, neurodegenerative disease and cardiovascular disease.Over the last decade, studies have advanced to the point that a number of inhibitors for these enzymes have been developed to attempt to ameliorate these conditions; some of the inhibitors are currently in human clinical trial. The need for this book is to review the current status of this field and the prospect for the inhibitors to be clinically important.