It is controversial whether bile salts are important in the pathogenesis of esophagitis. By sampling esophageal contents during ambulatory 24-h pH-monitoring we found that in a group of 18 patients with esophagitis all but 1 had detectable concentrations of bile salts in their esophagus. The concentrations of bile salts were low, however, and similar to those found in the gastric juice of 10 normal controls. It is concluded that bile salts are present in the esophagus of patients with esophagitis and that their presence results from duodenogastric reflux. The role of these refluxed bile salts in the pathogenesis of esophagitis is, however, unclear.