Eosinophilic esophagitis (EoE) is a chronic, Th2-type immune-mediated disorder. During the past decade, the increasing prevalence of EoE has been recognized in pediatric and adult populations all over the world. EoE diagnosis can be frequent challenging. Three criteria must be met to diagnose EoE: clinical symptoms of esophageal dysfunction, an esophageal biopsy with a peak eosinophil count of at least 15 eosinophils per high-power microscopy field and exclusion of other possible causes of esophageal eosinophilia. Although eosinophils mediate the EoE pathogenesis, proinflammatory cytokines are also critically involved. In the past years biologic therapeutics have revolutionized treatment of EoE.