In anaesthetized pigs gastrin release was stimulated by irrigation of the antrum with bicarbonate and by instillation of a meat extract. The concentration of gastrin and somatostatin was measured by radioimmunoassay both in the antral and peripheral venous blood. The increase in gastrin was coupled to a significant decrease in somatostatin immunoreactivity as measured in the antral venous blood both during instillation of alkali and meat extract. In peripheral blood, the differences were much less evident and not statistically significant. It is speculated that the decrease in release of antral somatostatin during alkalinization and instillation of meat extract is the primary event which is followed by a diminished inhibition of gastrin liberation. Thus, the present data support the hypothesis that antral somatostatin participates in the local regulation of gastrin release.