Dumping syndrome is a known complication of gastric surgery in adults, but a very rare disease in the pediatric population. We report on a case of dumping syndrome in a 19-month-old child, who underwent gastrojejunal feeding tube insertion for the treatment and prevention of gastroesophageal reflux and frequent aspiration pneumonia. At 17 months of age, 2 months after the beginning of gastrojejunal tube feeding, postprandial diaphoresis, palpitation, lethargy, bloating, and diarrhea occurred, and a single episode of convulsion with hypoglycemia were noted. Early and late dumping syndrome was confirmed by an abnormal oral glucose tolerance test with early onset hyperglycemia followed by delayed onset hypoglycemia. Diet therapy including uncooked corn starch then improved the postprandial diaphoresis, abnormal glucose levels, and her nutritional status. We conclude that dumping syndrome may be considered as a complication of gastrojejunal tube feeding in a child.