OBJECTIVES: Eosinophilic esophagitis (EoE) is a chronic antigen-mediated immune disorder of the esophagus. Consensus guidelines recommend obtaining esophageal, gastric, and duodenal biopsies at diagnostic endoscopy when EoE is suspected. The utility of repeated gastric and duodenal biopsies during follow-up endoscopy in patients previously diagnosed with EoE is not established. The aim of the present study was to explore the role of gastric and duodenal biopsies in children with an established diagnosis of EoE undergoing repeat endoscopy to assess histological response to treatment. METHODS: Retrospective chart review of children diagnosed with EoE at a tertiary care center was conducted. A total of 160 patients with EoE with demographic clinical, endoscopic, and histological data at diagnosis and follow-up endoscopy were included. The frequency of gastric and duodenal biopsies at follow-up endoscopy with abnormal histology and their correlation to endoscopic findings was determined. RESULTS: At follow-up endoscopy, 83% (132/160) of patients had gastric and 74% (118/160) had duodenal biopsies. Histology was normal in 81% of gastric and 92% of duodenal biopsies. The most frequent gastric abnormalities were chemical and inactive chronic gastritis. The most frequent duodenal abnormality was villous blunting with increased intraepithelial lymphocytes. Two patients with normal gastric and duodenal histology progressed to eosinophilic gastroenteritis at follow-up endoscopy. CONCLUSIONS: Gastric and duodenal biopsies obtained in EoE patients during follow-up endoscopy show pathology in a minority of patients, increase costs, and may add potential risk of adverse events. Large multicenter, prospective studies of endoscopic practice during follow-up of EoE are warranted to provide evidence supporting best practices.