Alterations of small intestinal sensory thresholds and small intestinal dysmotility are associated with functional dyspepsia. Because gastric and duodenal afferents partly project to the same areas, we postulated that patients with functional dyspepsia and H. pylori infection would be characterized by lower duodenal sensory thresholds. We evaluated 16 patients with functional dyspepsia and 16 age- and sex-matched controls. All patients had undergone an extensive diagnostic work-up to exclude organic lesions. Mechanosensitive function was tested in the third portion of duodenum utilizing a barostat device, and small intestinal motility was assessed before and during duodenal nutrient infusion with a five-channel low-compliance perfusion system. H. pylori status was assessed by a validated serological test. Small intestinal sensory thresholds (first perception and maximal tolerated pressure) were significantly lower in patients (21.1 +/- 2.1 and 30.9 +/- 1.8 mm Hg) compared to controls (33.0 +/- 2.2 and 38.8 +/- 0.9 mm Hg, all P < 0.003). Nine of 16 patients compared with five of 16 controls were H. pylori positive (P = 0.15). Thresholds for H. pylori-negative (28.7 +/- 2.8 and 36.5 +/- 1.1 mm Hg) or -positive subjects (25.0 +/- 3.0 and 32.7 +/- 2.4 mm Hg) were overall not significantly different (P > 0.3). However, in patients with defined high H. pylori titers (>50 units/ml) defined a priori, thresholds for first perception were significantly lower (14.7 +/- 2.9 mm Hg, N = 5) compared to patients with H. pylori titers below this threshold (24.3 +/- 2.9 mm Hg, N = 4) or without H. pylori infection (23.8 +/- 3.4 mm Hg, P < 0.05). During duodenal nutrient infusion, the duodenal motility index increased (P < 0.03). This increase was not significantly different in patients and controls or in H. pylori-negative or -positive subjects. Sensory abnormalities are present in patients with functional dyspepsia. In a small subgroup of patients with high H. pylori titers, sensory abnormalities may be linked to H. pylori infection.