Listeria monocytogenes is an important foodborne pathogen. It is commonly found in the environment, frequently present in the gut of cattle, poultry, and pigs and can be transmitted to ready-to-eat foods as well as raw meat products. However, no data are available on the prevalence of L. monocytogenes in organic foods. Throughout its history Listeria has been observed, studied and phylogenetically classified by numerous researchers. Because of the uncertainty of its phylogenetic position and its morphological similarity to the group of coryneform bacterium, names such as, Corynebacterium parvulum and Corynebacterium infantisepticumhave been used to describe the organism. In addition, serotyping and subtyping isolates of the pathogen L. monocytogenes is not only important for epidemiological reasons but for increasing our knowledge about the ancestry, evolution and virulence of this important foodborne pathogen