BACKGROUND & AIMS: Functional bowel disorders may follow acute intestinal infection. In animals, postinflammatory dysmotility is associated with nitrergic dysfunction. The aim of this study was to identify and characterize patients with presumed postinfectious dyspepsia (PD) compared with unspecified-onset dyspepsia (UD). METHODS: A total of 400 consecutive dyspeptic patients filled out a questionnaire to assess whether their symptoms were of postinfectious origin. They underwent testing for Helicobacter pylori infection as well as gastric emptying and gastric barostat studies. Pharmacological studies of nitrergic gastric function were performed in controls, in patients with presumed PD, and in patients with UD using sumatriptan, an activator of nitrergic neurons, and amylnitrite, a nitric oxide donor. RESULTS: Presumed PD was present in 17% of the patients and associated with more prevalent early satiety, weight loss, nausea, and vomiting compared with UD. Both groups did not differ in H. pylori infection, gastric emptying, or gastric sensitivity. Impaired accommodation was significantly more prevalent in patients with presumed PD (67% vs. 30%; P < 0.05). Sumatriptan relaxed the stomach in controls and patients with UD but not in patients with presumed PD, whereas amyl nitrite relaxed the stomach in all subjects. CONCLUSIONS: A subset of dyspeptic patients has a history suggestive of postinfectious dyspepsia. These patients have a high prevalence of impaired accommodation attributable to a dysfunction at the level of gastric nitrergic neurons.