Eosinophilic oesophagitis (EoE) is inflammation and swelling of the oesophagus as a result of an over-reaction of the immune system. Inflammation in the oesophagus can cause pain and discomfort when swallowing. EoE is now recognised as an allergic immune condition. More specifically, it is considered a form of food allergy due to patient sensitizations to foods and improvements in symptoms and inflammation after food eliminations. Symptoms include dysphagia, choking, food impaction, oesophageal strictures, gastroesophageal reflux disease, vomiting, food allergy, allergic rhinitis, atopy and asthma among others. Treament of EoE includes dietary elimination and steriod therapy. EoE can occur at all ages with 20% of patients diagnosed at childhood. Upper endoscopy and biopsies of the oesophageal mucosa must be performed to make an accurate diagnosis. All children in Ireland with suspected EoE are referrred for an endoscopy and biopsy to the single National Centre for Paediatric Gastroenterology, Hepatology and Nutrition (NCPGHN) in Our Lady’s Children’s Hospital, Crumlin. For this reason, the referral population to OLCHC closely approximates the national cohort of children diagnosed with EoE in Ireland. The primary aim of this study is to establish the ten-year paediatric prevalence of EoE in Ireland up to 31/12/15 and to profile the natural history of the disease including symptoms at presentation and response to different therapeutic treatments and remission rates on 2-3 year follow-up. This study will provide novel data on the prevalence of this condition in Ireland, and on the natural course of the disease after diagnosis.