There has not come to any definite conclusion on morphological changes in post-vagotomy gastric mucosa. And, it was reported that duodenogastric reflux in consequence of pyloroplasty or gastroenterostomy could aggravate these gastric mucosal changes. To elucidate this problem, 34 Wistar male rats were subjected to either truncal vagotomy, duodenogastric reflux procedure (transection of the lower part of the duodenum and gastrojejunostomy), or truncal vagotomy with duodenogastric reflux procedure. After 12 weeks, rats were killed for histologic studies of gastric mucosa. Rats subjected to vagotomy with duodenogastric reflux procedure showed marked atrophy of gastric glands, reduction in number of parietal cells and gastrin cells, formation of small ulcer, and generation of heterotopic glands. Rats subjected to duodenogastric reflux also showed chronic ulceration in the prepyloric region on the lesser curvature and hyperplasia of gastric glands. However, no remarkable changes were observed in the stomach of rats with vagotomy. These results indicate that chronic influence of postvagotomy duodenogastric reflux can lead to severe gastritis as well as altered structure of gastric mucosa.