In order to ascertain possible abnormalities in somatostatin and gastrin secretion in patients with duodenal ulcer, the author compared bombesin-stimulated somatostatin and gastrin secretion by antral mucosal explants in patients with duodenal ulcer, those with atrophic gastritis and normal controls. An organ culture technique was employed. This excluded neurogenic, hormonal and circulatory influences. Bombesin in concentrations of 10(-7) M to 10(-5) M stimulated gastrin and somatostatin secretion at a dose-dependent manner. In all subjects, bombesin (10(-7) M) stimulated antral gastrin release and increased explant gastrin content significantly (p < 0.05). Bombesin significantly increased somatostatin release and explant somatostatin content in normal subjects (p < 0.05) but not in patients with duodenal ulcer (p > 0.05). In the presence of bombesin, the total net increase of gastrin in medium and explants was greater in duodenal ulcer patients (31.57 +/- 5.20 ng/mg wet w.) compared with normal subjects (19.63 +/- 4.50 ng/mg wet w.) (p < 0.01). The total net increase of somatostatin in the presence of bombesin was significantly less in duodenal ulcer patients (0.10 +/- 0.02 ng/mg wet w.) than in normal subjects (1.45 +/- 0.24 ng/mg wet w.) (p < 0.01). The results suggest that abnormalities in somatostatin and gastrin secretion of the antrum contribute to the pathogenesis of increased gastric acid secretion in duodenal ulcer.