Abstract: A method, diagnostic sequences and primers are provided that are useful in identifying the Listeria monocytogenes and Listeria spp. The method involves identifying a RAPD-amplified DNA fragment common to Listeria monocytogenes, then identifying the most conserved regions of that DNA fragment, and the preparing specific primers useful for detecting the presence of a marker within the fragment whereby that set of primers is then useful in the identification of all Listeria monocytogenes. Markers within the same fragment that are specific to the Listeria genus are also identified and are useful for the identification of all Listeria spp.