The effect of linear somatostatin on pancreatic exocrine secretion in anaesthetized rats has been studied. Basal secretion of amylase was significantly inhibited by an infusion of 100 μg/100 g/h somatostatin, but increased fourfold after a bolus injection of 50 μg/100 g. CCK-stimulated enzyme and volume secretion were inhibited by somatostatin. Somatostatin did not influence secretin-stimulated bicarbonate concentration or rate of secretion in the dose range in which enzyme secretion was inhibited.