The genus of Raoultella (formerly Klebsiella) is a member of the family Enterobactericeae. Similar to other members, Raoultella spp are Gram-negative, aerobic, oxidase-negative, catalase- positive, non_motile  rods and are  capsulated such as Klebsiella.For differentiation of Raoultella from Klebsiella, 16SrRNA is using recently compare to biochemical test and DNA–DNA hybridization tests which were used before. In 2001, based on the histamine-producing strains and gene analyses the genus of Klebsiella spp. were reclassified, and the genus Raoultella including R. ornithinolytica, R. planticola and R. terrigena was separated. This article is extracted from the web search and review of 31 papers . In these studies different algorithms for differentiation of Raoultella from Klebsiella were suggested which are summarized in the recent review. The clinical implications of these bacteria are uncertain, nonetheless, the correct identification of bacterial species is essential to guide an effective antimicrobial treatment and improve clinical care. It was identified from the previous reports that the potential risk factors including invasive medical procedures, trauma with potential soil contamination and background diseases are related to the Raoultella spp. infections.