Gastroesophageal reflux (GER) is a term that describes the backflow of gastric content into the esophagus, sometimes reaching even the mouth. It is a common phenomenon and occurs in otherwise normal individuals several times during the day and night, especially after ingestion of fluids, e.g., soup, tea, coffee, or milk. Therefore, reflux episodes are more common in neonates and infants as long as they are nourished mainly with milk. The typical reflux symptoms in this age group are regurgitation, spitting up, and flaccid leak-out of milk after meals and when asleep. Pathological reflux defines a situation where the reflux causes symptoms in the neonate such as failure to thrive, sleep disturbance, and obviously, pain. The aim of this chapter is to discuss the normal esophagus in newborns and its function, the typical symptoms of reflux in this age group, investigating procedures, and conservative and operative therapy.