The effect of distal gastrectomy on gut hormone release was investigated by electrical stimulation of the posterior truncal vagus in dogs. Peripheral and portal plasma gastrin release was significantly inhibited, but peripheral and portal somatostatin release was unchanged. Peripheral and portal pancreatic polypeptide (PP) release was significantly inhibited. Our results suggest that the following factors might be some of the reasons why the secretion of PP was inhibited after distal gastrectomy: (l)transection of the posterior vagal branches close to the antrum and pylorus which might go to the pancreas; (2) changes in other hormones such as gastrin; (3) elimination of the PP secretagogue from the gastric antrum.