Eosinophilic esophagitis (EoE) is a clinicopathological entity characterized by a set of symptoms similar to gastroesophageal reflux disease and eosinophilic infi ltration of the esophageal epithelium. EoE is an emerging worldwide disease as documented in many countries. Recent reports indicate that EoE is increasingly diagnosed in both pediatric and adult patients although the epidemiology of this new disease entity remains unclear. It is unclear whether EoE is a new disease or a new classification of an old esophageal disorder. Esophagogastroduodenoscopy (EGD) and biopsies with histological examination of esophageal mucosa are required to establish the diagnosis of EoE, verify response to therapy, assess disease remission, document and dilate strictures and evaluate symptom recurrence of EoE. Repeated endoscopies with biopsies are necessary for monitoring of disease progression and treatment effi cacy. EGD has a fundamental role in the diagnosis and management of EoE, forming an essential part of the investigation and follow-up of this condition. EoE is now considered a systemic disorder and not only a local condition with an important immunological back-ground. One of the aims of research in EoE is to study non-invasive markers, such as immune indicators found in plasma, that correlate with local presence of EoE in esophageal tissues. Studies over the next few years will provide new information about diagnosis, pathogenesis, endoscopic/histologic criteria, non-invasive markers, novel and more eff icacious treatments, as well as establishing natural history. Randomized clinical trials are urgently called for to inform non-invasive diagnostic tests, hallmarks of natural history and more eff icacious treatment approaches for patients with EoE. The collaboration between pediatric and adult clinical and experimental studies will be paramount in the understanding and management of this disease. Eosinophilic esophagitis (EoE) is a clinicopathological entity characterized by a set of symptoms similar to gastroesophageal reflux disease and eosinophilic infi ltration of the esophageal epithelium. EoE is an emerging worldwide disease as documented in many countries. Recent reports indicate that EoE is increasingly diagnosed in both pediatric and adult patients although the epidemiology of this new disease entity remains unclear. It is unclear whether EoE is a new disease or a new classification of an old esophageal disorder. Esophagogastroduodenoscopy (EGD) and biopsies with histological examination of esophageal mucosa are required to establish the diagnosis of EoE, verify response to therapy, assess disease remission, document and dilate strictures and evaluate symptom recurrence of EoE. Repeated endoscopies with biopsies are necessary for monitoring of disease progression and treatment effiacy. EGD has a fundamental role in the diagnosis and management of EoE, forming an esse ntial part of the investigation and follow-up of this condition. EoE is now considered a systemic disorder and not only a local condition with an important immunological back-ground. One of the aims of research in EoE is to study non-invasive markers, such as immune indicators found in plasma, that correlate with local presence of EoE in esophageal tissues. that the correlate with local presence of EoE in esophageal tissues. that the correlate with local presence of EoE in esophageal tissues. of the next few years will provide new information about diagnosis, pathogenesis, endoscopic / histologic criteria, non-invasive markers, novel and more eff icacious treatments , as well as establishing natural history. Randomized clinical trials are urgently called for to inform non-invasive diagnostic tests, hallmarks of natural history and more eff icacious treatment approaches for patients with EoE. The collaboration between pediatric and adult clinical and experimental studies will be paramount in the understanding and management of this disease.