The vagal glucose signal pathway relevant to hepatic portal control of gastric acid secretion was examined in bilaterally adrenalectomized rats. The decrease in acid output after portal glucose injection was blocked by section of the hepatic branch which originates in the ventral vagus trunk below the diaphragm. After cervical vagotomy, the reduction in acid output was the same whether the section had been done on the right or the left side. The acid response was strongly inhibited by prior section of the dorsal vagus trunk at the celiac level. These results suggest that the hepatic glucose signal evoking an inhibitory action on the secretion of gastric acid has a specific pathway from the liver to the stomach, and that there is functional laterality in this pathway.