The article provides a comprehensive review of *Listeria monocytogenes*, a food-borne pathogen, including its characteristics, taxonomy, antigenic structure, epidemiology, and mechanisms of virulence. *L. monocytogenes* was first identified in 1929 and has since been implicated in several outbreaks of listeriosis in North America and Europe. The organism is a gram-positive, nonsporeforming, facultatively anaerobic rod that grows between −0.4 and 50°C. It is catalase positive, oxidase negative, and produces a β-hemolysin that acts synergistically with the β-hemolysin of *Staphylococcus aureus*. *L. monocytogenes* is widely present in various environments and can be found in plant, soil, and surface water samples, as well as in silage, sewage, slaughterhouse waste, and human and animal feces. The taxonomy of *Listeria* has been problematic, with multiple species and serovars identified. The current classification includes *L. monocytogenes*, *L. innocua*, *L. seeligeri*, *L. welshimeri*, *L. ivanovii*, *L. grayi*, and *L. murrayi*. The serovars of *L. monocytogenes* are classified into 13 serovars, with serovars 1/2a, 1/2b, and 4b causing most cases of human listeriosis. Human listeriosis is often associated with underlying conditions that suppress T-cell-mediated immunity, such as neoplastic disease, immunosuppression, pregnancy, extremes of age, diabetes mellitus, alcoholism, cardiovascular and renal collagen diseases, and hemodialysis failure. The clinical syndromes include central nervous system infections, primary bacteremia, and endocarditis. Neonatal listeriosis, particularly early-onset forms, has a high mortality rate, often due to pneumonia and respiratory failure. The incidence of listeriosis appears to be increasing worldwide, with a higher prevalence in Europe. Serovars 1/2a, 1/2b, and 4b are most commonly associated with human listeriosis. *L. monocytogenes* is a normal resident of the intestinal tract in humans, and carrier rates can be high, especially in pregnant women. The mechanisms of virulence of *L. monocytogenes* include its ability to grow intracellularly, use iron compounds, attach to host cells, and produce hemolysins. The hemolysin, listeriolysin O, is a major virulence factor that promotes intracellular growth and T-cell recognition. Other virulence factors include catalase and superoxide dismutase, which help the organism survive in activated phagocytes. Food-borneThe article provides a comprehensive review of *Listeria monocytogenes*, a food-borne pathogen, including its characteristics, taxonomy, antigenic structure, epidemiology, and mechanisms of virulence. *L. monocytogenes* was first identified in 1929 and has since been implicated in several outbreaks of listeriosis in North America and Europe. The organism is a gram-positive, nonsporeforming, facultatively anaerobic rod that grows between −0.4 and 50°C. It is catalase positive, oxidase negative, and produces a β-hemolysin that acts synergistically with the β-hemolysin of *Staphylococcus aureus*. *L. monocytogenes* is widely present in various environments and can be found in plant, soil, and surface water samples, as well as in silage, sewage, slaughterhouse waste, and human and animal feces. The taxonomy of *Listeria* has been problematic, with multiple species and serovars identified. The current classification includes *L. monocytogenes*, *L. innocua*, *L. seeligeri*, *L. welshimeri*, *L. ivanovii*, *L. grayi*, and *L. murrayi*. The serovars of *L. monocytogenes* are classified into 13 serovars, with serovars 1/2a, 1/2b, and 4b causing most cases of human listeriosis. Human listeriosis is often associated with underlying conditions that suppress T-cell-mediated immunity, such as neoplastic disease, immunosuppression, pregnancy, extremes of age, diabetes mellitus, alcoholism, cardiovascular and renal collagen diseases, and hemodialysis failure. The clinical syndromes include central nervous system infections, primary bacteremia, and endocarditis. Neonatal listeriosis, particularly early-onset forms, has a high mortality rate, often due to pneumonia and respiratory failure. The incidence of listeriosis appears to be increasing worldwide, with a higher prevalence in Europe. Serovars 1/2a, 1/2b, and 4b are most commonly associated with human listeriosis. *L. monocytogenes* is a normal resident of the intestinal tract in humans, and carrier rates can be high, especially in pregnant women. The mechanisms of virulence of *L. monocytogenes* include its ability to grow intracellularly, use iron compounds, attach to host cells, and produce hemolysins. The hemolysin, listeriolysin O, is a major virulence factor that promotes intracellular growth and T-cell recognition. Other virulence factors include catalase and superoxide dismutase, which help the organism survive in activated phagocytes. Food-borne