In this paper, surface active agents produced by microorganisms named biosurfactants are been discussed. This compounds have being identified and classified after long-term researches. The definition of biosurfacants and emulsifier, and their chemical structures and compositions were reviewed. Three main types of different biosurfactants have been identified : glycolipids, lipopeptides and phospholipids, which differ in molecular structures depending on their microbial producers. It can replace surface active com pounds of chemical origin in such areas like agriculture and industries (food, cosmetics, pharmaceutical, petrochemical and building).