Gastroesophageal reflux (GER) occurs frequently in infants, generally at its worst at 4 months of age, with approximately two-thirds of infants spitting up daily. GER typically improves after 7 months of age, with only ∼5% of infants continuing to have reflux at 1 year of age. The diagnosis can often be made based on clinical symptoms. Upper GI (UGI) study has low sensitivity and specificity and should not be ordered as a diagnostic test for reflux. UGI study is best for evaluating other anatomic causes of vomiting. GER becomes problematic gastroesophageal reflux disease (GERD) when complications are present, including feeding difficulties and poor weight gain. Conservative treatment and thickened formula can be helpful for treating GERD. Proton pump inhibitors (PPIs) are frequently prescribed for treating reflux. However, studies do not show a definite benefit in infants, and there are potential side effects. Older children with GERD may present with regurgitation, heartburn, chest discomfort, dysphagia, abdominal pain, vomiting, poor appetite, or poor weight gain. Upper endoscopy is considered for children with concerning symptoms, persistent symptoms despite treatment, and relapse of symptoms after treatment. Other esophageal disorders can have a similar clinical presentation as GERD, notably eosinophilic esophagitis (EoE). EoE is a chronic immune-mediated disorder of the esophagus, which may present as dysphagia, food impaction, heartburn, vomiting, abdominal pain, feeding difficulties, or failure to thrive. Diagnosis is made histologically by the presence of esophageal eosinophilia on endoscopic biopsies in the correct clinical setting.