This study has investigated the relationship between duodenogastric reflux, gastritis and certain symptoms 6-12 months after three operations for uncomplicated duodenal ulcer. The operations studied were proximal gastric vagotomy (PGV, 20 cases), truncal vagotomy and pyloroplasty (TV+P, 22 cases) and truncal vagotomy and antrectomy (TV+A, 21 cases). Duodenogastric reflux was assessed both by a radiological technique and by measuring the concentration of bilirubin in the gastric aspirate before and after operation. Incidence and severity of postoperative gastritis were determined by endoscopic biopsy. Symptoms were assessed by symptomatic score and Visick grading. There was a significant correlation between duodenal reflux and histological evidence of both severe superficial gastritis and glandular atrophy (P less than 0-01). There was also a close association between the degree of reflux and the presence of severe heartburn, epigastric pain and bile vomiting after operation. The amount of reflux did not differ before operation. There was significantly less reflux following PGV than after either TV+P (P less than 0-025) or TV+A (P less than 0-001). The results indicate that an operation which preserves an innervated and intact antrum and pylorus will protect against postoperative duodenogastric reflux, gastritis and symptoms.