We report on a case of dumping syndrome 1 month after Nissen fundoplication in a 5 month-old infant presenting with symptoms of late hypoglycemia. Blood glucose levels in pre- and post-prandial periods, oral glucose tolerance test and isotopic gastric emptying study confirmed the diagnosis. All symptoms resolved with diet therapy which could be stopped 8 months later. Dumping syndrome is not a so rare complication of gastric surgery and should be considered in patients with non specific symptoms.