['Because of complications and its invasive nature, fundoplication is often a treatment of last resort for children with gastroesophageal reflux. Gastroesophageal reflux testing does not always predict who will benefit from antireflux surgery. Furthermore, there are no studies to determine whether a higher preoperative reflux burden, including acid and nonacid reflux, is associated with an improved postfundoplication outcome. The aim of the study was to determine predictors of fundoplication outcome including acid and nonacid reflux burden.', 'We retrospectively reviewed preoperative pH-multichannel intraluminal impedance tracings and medical records of 34 patients who underwent fundoplication. Patients were categorized as improved or not improved, and the demographic and reflux characteristics were compared between groups. Multivariate analysis was performed to determine predictors of outcome.', 'No single reflux marker, including the number of acid, nonacid, total events, or the percentage of time that reflux was in the esophagus, predicted fundoplication outcome (P > 0.1). Neither a positive symptom index nor a positive symptom sensitivity index predicted postoperative improvement (P > 0.4). Receiver operating characteristic curve analysis failed to reveal an ideal value to maximize sensitivity for either the symptom index or the symptom sensitivity index.'] Do reflux events detected by pH-MII determine fundoplication outcome?