The pathologic reports of all 1,020 esophageal biopsy specimens obtained between 1975 and 1981 in patients with symptoms of gastroesophageal reflux were reviewed. Barrett's esophagus was identified in 84 patients (8 percent). The 362 patients seen between 1980 and 1981 were reviewed in detail. The symptoms in patients with Barrett's esophagus differed from those of the patients without Barrett's esophagus. Dysphagia was more often present in the former group (34 percent versus 16 percent, p less than 0.05) and epigastric distress was less frequent (11 percent versus 27 percent, p less than 0.05). Objective findings of hiatal hernia, esophageal stricture, and esophageal ulcers occurred more commonly in patients with Barrett's esophagus than in those without Barrett's esophagus (70 percent versus 48 percent, 31 percent versus 4 percent, and 14 percent versus 6 percent, respectively, p less than 0.05). Mid esophageal strictures were associated almost exclusively with Barrett's esophagus (five of six patients). At esophagoscopy, erythema was seen more commonly with Barrett's esophagus. The diagnosis was suspected by the endoscopist in only 34 percent of patients subsequently demonstrated histopathologically to have Barrett's esophagus. There was no significant difference in the prevalence of a positive Bernstein test result or gastroesophageal reflux on upper gastrointestinal series in patients with and without Barrett's esophagus. However, a hypotensive lower esophageal sphincter was found more commonly in patients with Barrett's esophagus (100 percent versus 53 percent, p less than 0.05). Thirteen of the 84 patients with Barrett's esophagus (15 percent) had a coexistent adenocarcinoma arising from Barrett's mucosa. These patients, when compared with the patients with Barrett's esophagus without carcinoma, were more often male (77 percent versus 51 percent, p = 0.1), more often had dysphagia (69 percent versus 34 percent, p less than 0.05), and more frequently had a comparatively short duration of symptoms (67 percent versus 36 percent, p less than 0.05). Our findings suggest that patients with Barrett's esophagus have a high risk of development of carcinoma. Because the entity is often not recognized at endoscopy, routine esophageal biopsy should be performed on all patients undergoing esophagoscopy for symptoms of gastroesophageal reflux. Patients with known Barrett's esophagus should be followed closely with repeated endoscopy and biopsy.