Exosomes are cell-derived lipid bilayer vesicles of 30 to 150?nm that contain diverse proteins, lipids, and nucleic acids. Exosomes are important conveyers of information between cells, through the transmission of various proteins, bioactive lipids and genetic information to alter the phenotype and function of recipient cells. In addition, exosomes are closely related to the occurrence and development of cancer, infectious diseases and neurodegenerative disorders. Targeting exosomes directly to inhibit their deleterious effects in mediating disease or exploiting their inherent potential to stimulate regenerative responses or to deliver nucleic acids and other drug cargoes across major biological barriers are emerging as important novel therapeutic strategies. The function of exosomes depends on the recognition, binding and uptake of exosomes by recipient cells, while the progress depends on the type and effective function of exosomal membrane proteins. Exosomal membrane proteins and their function were described in this paper.