This study was undertaken to evaluate the incidence and severity of postoperative alkaline reflux gastritis in 798 symptomatic duodenal ulcer patients who had undergone vagotomy. The condition was identified on the basis of the unique endoscopic and histological findings in 116 (14.5%) of them. It was more frequent and severe in patients with truncal vagotomy and gastrojejunostomy than in those with truncal vagotomy and pyloroplasty, while it was not at all observed in cases with proximal gastric vago-tomy, the symptoms depended on the preoperative history of the ulcer disease and the patient's age at the time of surgery, but did not always correspond with the degree of histological findings. The location of the gastrojejunostomy and the size of the pyloroplasty stoma had an influence on the incidence of the syndrome. Helicobacter pylori was found more frequently in biopsy specimens from patients with severe symptoms (30.3%), but was present in only 14.6% of the total number of the patients with postoperative alkaline reflux gastritis after vagotomy.