Dogs were provided with oesophageal fistulae, fully innervated pouches of the fundic stomach and the duodenal bulb, and a gastric cannula. Gastric secretion was stimulated by sham feeding for 10 min. The bulbar pouches were perfused either with 0.9 per cent NaCl or with 0.1 N HCl. Plasma gastrin concentrations were determined by radioimmunoassay. Bulbar acidification effectively inhibited gastric acid secretion. Plasma gastrin responses were not suppressed. Instead, plasma gastrin concentrations were higher than in controls. The results show that the bulbar mechanism does not inhibit gastric acid secretion by reducing gastrin release.