Phenolic Glycolipids (PGLs) are constituents of the mycobacterial cell envelope that are uniquely produced by human mycobacterial pathogens such as M. tuberculosis, M. bovis, M. leprae and M. ulcerans. PGL-1 is suspected to play a critical role in the pathogenesis of leprosy. This book provides a comprehensive discussion about the Oligosaccharides of PGLs epitopes identification, synthesis, and the molecular mechanisms involved in the mycobacterial diseases pathogenesis.