The first report of human infections due to Campylobacter dates back to 1947. These microorganisms, classified initially as Vibrio, had been known for many years as agents of several diseases in animals. In 1963 they were grouped in the new Genus Campylobacter belonging to Spirillaceae. Campylobacter are ever more important, particularly C. jejuni, which is an ubiquitous agent of diarrhoea in children. Other microorganisms of this Genus, the "gastric Campylobacter-like organisms" type I, otherwise known as Campylobacter pyloridis, are responsible for gastric diseases.