Aims: The aims of this study were to evaluate the prevalence and clinical characteristics of heterotopic gastric mucosa of the upper esophagus (HGMUE), and to examine its association with gastroesophageal reflux in patients with pharyngeal symptoms. Methods: Patients (879:407 male, 472 female) who underwent endoscopy for upper digestive symptoms from March to September 1998 were enrolled. Their upper esophagus could be observed with full expansion. All patients were carefully questioned, especially with regard to pharyngeal and esophageal complaints. Twenty-four-hour esophageal pH monitoring using a 2 channel catheter was performed in patients who had pharyngeal symptoms. Results: HGMUE was observed in fifty-six cases (6.4%). Forty-five (80.4%) of the 56 patients with HGMUE were asymptomatic and 11 patients complained of pharyngeal discomfort. Among 8 patients with HGMUE who complained of pharyngeal discomfort and underwent 24-hour esophageal pH monitoring, 5 patients showed acid reflux in lower esophagus, but no reflux in pharynx. Conclusions: This study demonstrates that HGMUE is a rather common asymptomatic benign lesion. Patients with HGMUE who have pharyngeal discomfort seem to have gastroesophageal reflux disease. Endoscopic examination of upper esophagus is needed in patients with pharyngeal discomfort. (Kor J Gastroenterol 2000;35:276 - 282)