Acute infectious gastroenteritis is the strongest known risk factor for the development of irritable bowel syndrome (IBS), one of the most common functional gastrointestinal disorders. The knowledge about the incidence and prevalence of post-infectious IBS (PI-IBS) in the general population is still limited. Risk factors have been identified in the development of PI-IBS. These include the virulence of the pathogen, younger age, female sex, the long duration of the initial illness and the presence of psychological disturbances. Histopathologic data demonstrate a low-grade mucosal inflammation in a subset of patients with IBS. Furthermore, a change in intestinal microflora could also be involved although confirmatory studies are required. The use of probiotics or non absorbable antibiotics during the acute infective episode could play a preventive role. Nonetheless, the discovery that an infective episode may trigger the development of IBS has not substantially changed the clinical management of this subset of patients compared to the classical (non infective) form of IBS. Future studies aimed at identifying specific therapies are waited.