ObjectivesBile reflux has been postulated to be an important factor contributing to gastroesophageal reflux disease in adults. The purpose of this study was to investigate its role in children.MethodsSixty‐five children with symptoms of gastroesophageal reflux disease were classified on the basis of the endoscopic grade of reflux esophagitis: no esophagitis (n = 26), mild to moderate esophagitis (n = 26), and severe esophagitis (n = 13). Simultaneous 24‐hour esophageal pH and bilirubin monitoring with Bilitec 2000 was performed.ResultsBoth bile and acid reflux increased with the severity of esophagitis. The differences between all groups were significant for the percentage of total (P < 0.0005), upright (P < 0.05), and supine time (P < 0.0005) bilirubin absorbance ≥ 0.14, as well as for the percentage of total and supine time pH < 4, and DeMeester score (P < 0.0005). Combined pathologic acid and bile reflux was found in 11% of children with mild esophagitis and in 70% of children with severe esophagitis, while isolated bile reflux was found in 31% and 7.5%, respectively. Combined pH and bilirubin monitoring, compared with ph‐monitoring alone, increased the sensitivity from 56% to 79%, and the accuracy from 69% to 83%.ConclusionsBoth bile and acid reflux increase stepwise with the severity of esophagitis.Combined acid and bile reflux is associated with severe esophagitis. Isolated acid or bile reflux is usually present in mild esophagitis.Simultaneous esophageal pH and bilirubin monitoring has a higher sensitivity, as well as predictive values and accuracy than ph monitoring alone.