Campylobacter pylori is thought to be confined to gastric mucosa; when detected in the duodenum in association with duodenal ulceration, the organism infects only areas of gastric metaplasia. Barrett's esophagus is a metaplastic condition of the esophagus, in which areas or islands of "gastric-type" epithelium are found. To determine whether C. pylori colonized the esophagus of patients with Barrett's esophagus, we studied retrospectively 23 unselected patients who had endoscopic and biopsy evidence of Barrett's esophagus. Mucosal biopsy specimens were stained by the Warthin-Starry silver technique and reviewed by an experienced, "blinded" histopathologist. Of the 23 patients, 12 (52%) had C. pylori in the esophagus. Patients with and those without C. pylori were of similar age and gender, had similar scores for acute and chronic inflammation, and had similar lengths of tubular esophagus with metaplastic gastric mucosa. These observations suggest that C. pylori commonly infects Barrett's esophagus. The clinical importance of this finding is unknown.