Radiofrequency ablation (RFA) with HALO system has been developed as a new treatment option for Barrett's esophagus (BE). It had been observed that some patients had esophageal eosinophilia (EE) infiltration after RFA. The incidence and features of EE after RFA were systematically determined. From a prospectively compiled database, data on 148 patients who underwent RFA for BE were analyzed. Biopsies were taken pre- and post-RFA from the BE segment, and histological sections of the biopsy specimens were stained with hematoxylin and eosin, and examined by a gastrointestinal pathologist. The incidence of EE post-RFA was then determined. Of the 148 patients, 120 (81%) were men, 137 (92%) were white, 64 (43%) were overweight and 49 (33%) obese, and 128 (86%) were over 50 years of age or more. Four (2.7%) of the patients developed post-RFA EE, but none had symptoms of eosinophilic esophagitis. All patients except one had a history of seasonal allergies. All four were taking proton pump inhibitor before and after RFA. Two patients with EE drank alcohol, one of which was a smoker. EE is a potential adverse event of RFA for BE. The absence of esophageal dysfunction symptoms suggests a different clinicopathological entity from eosinophilic esophagitis. Further studies should be done to assess its clinical significance, if therapy is needed, or if it may eventually lead to eosinophilic esophagitis.