In humans, Leishmania is an obligatory intracellular parasite of the mononuclear phagocyte system, wherein the microorganism multiplies. These pathogenic protozoa are transmitted by sandflies and reside in the digestive tract of the vector insects. There is increasing evidence that specialised surface and secreted molecules of Leishmania are virulence factors essential for colonization of the sandfly vector as well as for parasite invasion and subsequent survival in the macrophage. Recent research in our laboratories has focused on the identification and molecular characterisation of a unique family of mucin-like proteophosphoglycans (PPGs) present on the surface, and secreted by promastigotes and amastigotes. In this review we provide an overview of the current knowledge of the structure and function of this new class of proteoglycans. The elucidation of their primary structure reveals unique proteins, phosphoglycan structures and protein-carbohydrate linkages which, together with their proposed function(s), provide attractive targets for the development of vaccines and antiparasite drugs.