AbstractThe bombesin (BBS) infusion test was performed in 232 subjects with a variety of conditions, including 35 normal individuals, 41 duodenal ulcer patients, 13 gastric ulcer patients, and 14 patients with Zollinger‐Ellison syndrome. Side effects occurred in 80% of patients, but in only 6% was the test discontinued due to discomfort. All side effects promptly subsided when BBS infusion was interrupted. The dose of BBS eliciting the maximal gastrin response was 15 ng/kg per minute. In man, BBS showed a powerful stimulatory action on antral and gastrinoma G cells. No effect on duodenal G cells was apparent. Plasma levels of the different molecular forms of gastrin were all augmented by BBS infusion. BBS potentiated the gastrin response to a meal and elicited a prolonged and sustained gastrin response in patients with Menetrier's disease. Cells with BBS‐like immunoreactivity were demonstrated in the gastrointestinal tract of man. These data suggest that BBS may play a physiologic role in man.The clinical value of the BBS test was mainly assessed in the study of patients with postgastrectomy recurrent ulcer. In these patients, the BBS test clearly segregated patients with hypersecretion of gastrin from patients without such hypersecretion, and helped to elucidate the pathophysiologic features causing hypergastrinemia.In perspective, BBS should be viewed as an endocrine polyreleaser (gastrin, CCK, PP, glucagon) and as a member of the family of immunoreactive brain‐gut peptides. The role of BBS in the “brain‐gut axis” remains to be determined.