Markedly increased esophageal eosinophils are associated with allergy- or reflux-based eosinophilic esophagitis. Other known disorders that cause this entity are unusual. To characterize the clinical, endoscopic, and histological findings of patients who develop marked esophageal eosinophilic infiltration after ablative therapy for Barrett's dysplasia. All patients who underwent endoscopic ablation of Barrett's esophagus between 1991 and 2009 with photodynamic therapy or radio frequency were screened for a pathologic descriptor of ‘eosinophils’ on biopsy. Patients whose biopsies demonstrated >15 eosinophils per high power (HPF) field in squamous epithelium after ablation were reviewed and included in the study group. Thirteen of 385 (3.4%) patients underwent ablation for Barrett's esophagus and subsequently had large numbers of intraepithelial eosinophils. All patients had long segment Barrett's (mean 8.0 cm) with low- or high-grade dysplasia or adenocarcinoma. All had undergone photodynamic therapy as their form of ablation. No patients had typical symptoms or endoscopic findings of eosinophilic esophagitis. Eleven patients were on proton pump inhibitors. The time between ablation and onset of esophageal eosinophilia ranged from 83 to 692 days. Intraepithelial eosinophil counts ranged from 30 to 150/HPF (mean 90). The majority of cases showed eosinophilic degranulation, spongiosis, increased papillary height, and basal zone thickening. The natural history of esophageal eosinophilia was variable after ablation, persisting consistently or sporadically on biopsy for up to 6 years. Ablation for Barrett's dysplasia can be followed rarely by eosinophil infiltrates with a histological resemblance to allergy-based eosinophilic esophagitis, but lacking dysphagia. The pathophysiology is unknown.