SUMMARY1. Electrical stimulation of the vagus nerves produced a parallel increase in gastric acid secretion and gastric mucosal blood flow.2. Gastric acid secretion and mucosal blood flow, stimulated by pentapeptide infusions or by vagal stimulation, were markedly and equally reduced by electrical stimulation of splanchnic nerve fibres.3. The splanchnic stimulated reduction in acid and mucosal blood flow occurred only when the rise in blood pressure, normally associated with splanchnic stimulation, was prevented by inclusion of a pressure reservoir in the circulation.4. There was evidence that the effect of the splanchnic nerves was not mediated by release of adrenaline from the adrenal medulla.