Gastroesophageal reflux was looked for in 51 children with chronic obstructive respiratory disease (CORD) using prolonged pH monitoring. An index of reflux aggressivity dependent on both duration and acidity of refluxed material was calculated. This index was significantly related to the macroscopic endoscopic findings, patients with an elevated acidity index having more severe "endoscopic esophagitis" than patients with a normal acidity index. We conclude that the finding of normal, erythematous or destructive esophagitis at endoscopy has at least some clinical relevance.