Eosinophilic esophagitis (EoE) is a chronic inflammatory condition characterized clinically by symptoms of esophageal dysfunction and histologically by dense eosinophilic infiltration. Its pathogenesis involves an immune-mediated response to environmental antigenic stimulation. The incidence and prevalence are increasing and EoE has become the most common cause of dysphagia and food impaction in adults. Its management often requires a multi-disciplinary approach as treatment includes specialized diets, anti-eosinophilic medications and esophageal dilation once fibrostensosis has developed. This book discusses the causes, symptoms and treatment options of eosinophilia.