In children with medically refractory gastroesophageal reflux disease (GERD), fundoplication is effective and safe. However, in a subset of patients, gastrointestinal dysfunction occurs postoperatively. Symptoms include chest pain, persistent dysphagia in 5%, gas bloat in 2% to 4%, diarrhea in up to 20%, and dumping syndrome in up to 30%. Symptoms are often nonspecific, arising from recurrent or persistent GERD, anatomic complications such as disrupted or herniated wrap, functional disturbances such as rapid gastric emptying or altered gastric accommodation, or alternative diagnoses such as cyclic vomiting syndrome or food allergy. Detailed investigation, including various combinations of pHmetry, videofluoroscopy, endoscopy, motility studies, and dumping provocation testing, may be required to clarify pathophysiology and guide management.