Viable but non-culturable (VBNC) bacteria concept has been defined in 1982 when it has been shown that there exists bacteria whose metabolic activity continue and which can have the ability to reproduce in suitable conditions although they have lost their capability to reproduce in culture. Recent studies have shown that most of the human pathogens (Campylobacter spp., Escherichia coli, Francisella tularensis, Helicobacter pylori, Legionella pneumophila, Listeria monocytogenes, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Vibrio cholerae, V.parahaemolyticus, V.vulnificus) have VBNC form. The interest on this subject has increased due to the detection of some disinfection procedures such as pasteurization of milk and chlorinization of water, cause bacteria to switch to VBNC form. It is thought that, the bacteria in this form may have an important role in recurrent and drug resistant infections as well as infections of unknown origin. However, advanced studies should be done to clarify the role of VBNC bacteria in the setting of recurrent infections, together with their pathogenity and antibiotic resistance. In this review article, the importance of viable but non-culturable bacteria, their morphology, metabolic and genetic properties, pathogenity, resuscitation and identification have been discussed.