In dogs with vagally innervated gastric pouches, a study has been made of the effect of a truncal vagotomy on gastric hypersecretion induced by extensive small bowel resection. Truncal vagotomy after small bowel resection produced a marked reduction in the early part of the acid all response to a meal, but was without effect on the later increased part of the response to the meal, or on the total 24-hour secretion induced by the intestinal resection.