Throughout the world, foodborne pathogens are still causing many intestinal diseases in humans, resulting in substantial health and economic burdens. In the United States, where the food supply is one of the safest in the world, one in four people still experience a foodborne illness every year. The frequency and the significance of these foodborne illnesses depend on the interaction between the foodborne pathogen, the host, the food, and the environment. The majority of the reported foodborne illness outbreaks are caused by known pathogens such as Norovirus, Campylobacter, Salmonella, Listeria monocytogenes, and Shiga toxin-producing Escherichia coli. Other pathogens that are reported to occasionally cause illnesses are Staphylococcus aureus, Clostridium species, Bacillus cereus, Yersinia enterocolitica, parasites, and others. Typical symptoms of foodborne illnesses include abdominal pain, diarrhea, vomiting, nausea, fever, respiratory difficulties, and, in severe cases, death. These symptoms are caused by the ingested pathogens, as in the case of foodborne infections (Salmonellosis, Listeriosis, etc.) or by the microbial toxins produced inside the host as in the case of toxico-infections (Clostridium perfringens food poisoning, etc.). In the case of foodborne intoxications, the toxins produced by the pathogen in the foods cause symptoms (Botulism, Staphylococcal food poisoning, etc.). Food products that have been incriminated in the most outbreaks are poultry, ground meat, seafoods, milk & dairy products, and fruits & vegetables. This chapter introduces foodborne pathogens, describing their morphological and biochemical characteristics, their pathogenesis and clinical symptoms, and the associated foods.