BACKGROUND AND AIM: Duodenal acidification might increase sensitivity to gastric distension, which seems to play a role in the genesis of dyspeptic symptoms in a subset of patients with functional dyspepsia. The aim of the present study was to investigate the characteristics of dyspeptic symptoms associated with hypersensitivity to gastric distension induced by duodenal acidification. METHODS: An infusion tube and a barostat bag were positioned in the duodenum and gastric fundus, respectively. Sensitivity to stepwise fundic distensions with severity scoring of the seven dyspeptic symptoms was assessed before and during duodenal acid infusion in 20 healthy subjects. RESULTS: Acid infusion significantly decreased the pressures and the corresponding wall tensions at the thresholds for discomfort. At the distending level of minimal distending pressure (MDP) + 2 mmHg, significantly higher scores of fullness and bloating were obtained during acid infusion. With distending stimuli of MDP + 4 and 6 mmHg, fullness, bloating, nausea, satiety, epigastric burning and epigastric pain were significantly more severe during acid infusion than before acid infusion. At the level of MDP + 8 mmHg, the severity of epigastric pain was significantly greater, compared with that before acid infusion. CONCLUSIONS: Duodenal acidification might aggravate dyspeptic symptoms through the induction of hypersensitivity to gastric distension in healthy individuals. Those symptoms are diverse and variable, depending on the strength of the distending stimuli.