Symptoms of gastroesophageal reflux disease (GERD) occur in 2% to 7% of children. The manifestations of GERD can be limited to symptoms (eg, heartburn, regurgitation) or can be more complicated, such as erosive esophagitis, esophageal strictures, or Barrett esophagus. The prevalence of such GERD complications in children is unknown. The purpose of this study was to determine the prevalence of endoscopic findings of erosive esophagitis in children. All children ages 0 to 17 years, 11 months who underwent upper endoscopy that was recorded in the Pediatric Endoscopic Database System-Clinical Outcomes Research Initiative between 1999 and 2002 were included. Endoscopic reports that were incomplete or that did not include demographic features, indications for endoscopy, or endoscopic findings were excluded. Erosive esophagitis was defined either descriptively or by the Los Angeles classification. Esophageal biopsy was not evaluated. A total of 7188 children who underwent upper endoscopy fulfilled the inclusion and exclusion criteria. Of those, 888 (12.4%) had erosive esophagitis. The median age of children with erosive esophagitis was 12.7 +/- 4.9 years versus 10.0 +/- 5.1 years in those without erosive esophagitis (P <or= 0.0001). Of those with erosive esophagitis, 55.2% (490/888) were male, compared with 48.2% (3040/6300) in those without erosive esophagitis (P = 0.0001). Erosive esophagitis was found in 29 of 531 (5.5%) children ages 0 to 1 years and progressively increased to 106 in 542 individuals (19.6%) by age 17. Hiatal hernia was found in 68 (7.7%) of children with erosive esophagitis, compared with 157 (2.5%) without erosive esophagitis (P <or= 0.0001. The prevalence of Barrett esophagus, esophageal stricture, ulcer, previous surgery, nodules, foreign body or retained food, and anatomic abnormalities was not significantly different between children with erosive esophagitis and those without. The frequency of erosive esophagitis is slightly higher in male children and increases with age. In contrast to erosive esophagitis in adults, there were no significant variations according to race or ethnicity. Hiatal hernia is the only endoscopic observation that predicts erosive esophagitis.