Eosinophilic esophagitis (EoE) is a chronic inflammatory disease characterized by eosinophilic infiltration and inflammation of the gastrointestinal tract in the absence of other causes of tissue eosinophilia. The clinical course of EoE like gastroesophageal reflux disease with eosinophilic infiltration of the esophageal epithelium. EoE widely diagnosed abroad in children and adults, whereas in Russia the disease is almost never diagnosed. Upon detection of eosinophilia in the biopsy of the esophagus should exclude other causes. The correct clinical diagnosis in combination with the study of biopsy tissue of the esophagus and other laboratory methods (including allergic testing) is crucial in achieving the effectiveness of therapy EoE.