Gastroesophageal reflux (GER) is the movement of gastric contents retrograde into the esophagus. Sometimes the refluxate is seen as emesis, but often reflux is ''silent,'' meaning that there are no discrete symptoms during an episode. In adults, the most common symptom of GER is heartburn, whereas in infancy excessive crying and malaise are symptoms that prompt investigation for GER,with or without esophagitis. Symptoms of esophagitis in infancy may include arching (hyperextension) of the torso and refusal of feedings. Tube feedings may be required to treat infants with failure to thrive who refuse oral feedings. Paradoxically, tube feedings increase the number of GER episodes. A hypothetical explanation for refusal of food in infancy is that pain with swallowing (odynophagia) or heartburn are consequences of peptic esophagitis. As a result, infants will learn to refuse food if it hurts or if they fear that it will hurt to eat. Another possible mechanism is visceral hyperalgesia, a neuropathic condition in which prior experience changes sensory nerves so that previously innocuous stimuli are perceived as painful. Some infants may have especially sensitive sensory nerves in the upper gastrointestinal tract, which predisposes visceral hyperalgesia to develop. Thus pain occurs from luminal distension or acid reflux in the absence of tissue damage. The evaluation of babies who won't eat includes a careful history and physical examination to exclude the possibility of chronic systemic illness. Refusal to feed is an unusual manifestation of a common condition: GER disease. The initial tests for GER usually include a barium swallow study to assess the upper gastrointestinal anatomy, endoscopy and esophageal biopsy to assess esophagitis, and an intraesophageal pH study, which is useful in ''silent'' reflux to quantitate the duration of esophageal acid exposure and to correlate discrete symptom episodes with periods of reflux. The treatment of infants and toddlers who refuse to eat because of pain resulting from visceral hyperalgesia or reflux esophagitis involves removing the pain associated with eating and making eating a pleasurable experience. Treatment for esophagitis may include maintaining an upright posture after meals and thickened feeds, medication to improve gastrointestinal motility or to decrease acid secretion, or fundoplication.