BACKGROUND AND AIMS: The major complications of reflux esophagitis are stricture formation and Barrett's esophagus. In Korea, the incidence of these complications is low and most patients with reflux esophagitis undergo a mild clinical course. The purpose of this study was to investigate patterns of acid reflux and esophageal motility in mild reflux esophagitis in Korea. METHODS: Using conventional manometry and 24-hour ambulatory pH monitoring, we were investigated esophageal motility and patterns of gastroesophageal reflux in 41 patients with reflux esophagitis Savary-Miller (S-M) Ib using on endoscopy. The total supine, and upright reflux periods, as well as frequency and duration of reflux episodes were determined from the 24-hour pH monitoring record using standard software. Pathologic reflux was defined when the percentage of the total time with pH less than 4 (acid exposure time) exceeded 4%. RESULTS: Pathologic reflux was observed in 17 patients (41.5%), who were categorized into upright refluxers (70.6%), supine refluxers (11.8%), and combined refluxers (17.6%). Patients with reflux esophagitis did not differ in lower esophageal sphincter pressure from the normal subjects. There were two patients (4.9%) with a lower esophageal pressure > or =10 mmHg and four patients (9.8%) with hiatal hernia. Failed peristalsis was seen in 4 patients (9.8%). CONCLUSIONS: A high proportion of upright reflux and low incidence of esophageal peristaltic dysfunction may contribute to the low incidence of stricture formation and Barrett's esophagus in patients with mild reflux esophagitis in Korea.