Extensive small bowel resection produces pancreatic hyperplasia and increases plasma gastrin levels in the rat. Because gastrin is known as a trophic factor for the exocrine pancreas, we studied the effect of endogenous variations of gastrin induced by different gastric operations on the rat pancreas in both resected and transected animals. Vagotomy increased plasma gastrin level while antrectomy decreased it; pyloroplasty was without any effect. These gastric operations enhanced slightly but not significantly the pancreatic weight, its protein and DNA content. A 90% jejunoileal resection alone increased markedly these parameters while mitotic figures appeared in acinar cells. Pyloroplasty, vagotomy and antrectomy did not modify the changes induced by intestinal resection itself except the level of protein. These findings suggest that hypergastrinemia produced by intestinal resection is not responsible for pancreatic hyperplasia.