An experimental study was conducted on the effect of resection of the jejunum and ileum on gastrin release. The intravenous infusion of L. arginine in a dose of 0.5 g per kg body weight for 30 minutes proved to be most practical in evaluating gastrin release in addition to insulin and glucagon release. Serum gastrin levels in response to this dose of arginine were determined before and three weeks, three months and one year after resection of the jejunum and of the ileum. At three weeks, a significant increase in gastrin levels occurred in bothe the fasting state and after stimulation in dogs with either jejunum or ileum resection. At three months, the elevated gastrin response persisted only in those with jejunum resection. By one year, the gastrin levels had fallen in almost all dogs to approximately the preoperative levels.