Eosinophilic esophagitis (EoE) is an emerging chronic immune and antigen-mediated clinicopathologic disease. During the last 2 decades, the incidence of this condition in children have increased significantly, thanks to more awareness of practitioners and higher use of diagnostic endoscopy. We have analysed paediatric literature on EoE focusing on epidemiology, pathophysiology, clinical findings and diagnostic approach. EoE is pathogenically related to a Th2 inflammation characterized by a mixed IgE and non IgE-mediated reaction to food and/or environmental agents. This leads to esophageal dysfunction and remodeling accompanied by subepithelial fibrosis. EoE presents with a diverse range of gastrointestinal symptoms, including regurgitation, vomiting, feeding difficulties or feeding refusal in infants and toddlers, as well as heartburn, dysphagia and food bolus impaction in older children and adults. The diagnostic suspicion is based on the presence of chronic symptoms of esophgeal disfunction and esophageal eosinophilia characterised histologically by a significant eosinophilic infiltration of the oesophageal mucosa (>15 eosinophils per high powered field). In this review we will provide an update on clinical presentation and diagnostic approach to EoE in children. We emphasized the relevant aspects of the new clinical condition termed "PPI responsive esophageal eosinophilia", as entities distinct from EoE and the role of PPI trial in diagnostic workup, therefore we proposed a new diagnostic algorithm.