Introduction: Background & AIMS: Eosinophilic esophagitis and PPI-REE patients appear related but no clinical, endoscopic, or histologic distinguishing features have been identified. However, it is likely that subtle differences exist that differentiate these entities. Our aim was to assess for a difference in the timing and extent of esophageal stricture formation, the cardinal feature of adults with EoE, with correlation to other patient characteristics. Methods: We performed a retrospective cohort analysis on data collected from 2004 to 2015. Cases were patients with dysphagia >18 years of age with > 15 eos/hpf on esophageal biopsy and no other identifiable cause of eosinophilia. All patients were treated with BID PPI therapy and had a follow up EGD with biopsies after 6-8 weeks. Demographic, clinical, endoscopic, histologic and barium swallow findings measured for maximal and minimal esophageal diameters were collected. Patients with minimal diameter (15mm) were further classified as a) Small caliber esophagus (defined as decreased min diameter >8cm in length), b) stricture (1-7cm length), and c) esophageal ring (< 1 cm in length). Results: 69 patients with EoE and 29 patients with PPI-REE were analyzed. PPI-REE and EoE patients demonstrated a similar prevalence (%) of heartburn (60 vs. 62), extraesophageal allergies (63 vs. 57), eczema (88 vs. 82), food impaction (85 vs. 86), mean peripheral eosinophil count ( 0.20 vs. 0.20), and stricture or rings (19 vs. 28, 37 vs. 38 respectively, all p>.05). No gender or race differences were noted (Male 58 vs. 58, Caucasian 97 vs. 97%)p>0.05). Endoscopic findings of linear furrows, rings, white spots or stricture were additionally similar between groups ( 45 vs. 52, 60 vs. 66, 60 vs. 65, 14 vs. 10, 25 vs 21 respectively, all p>.05). In contrast, EoE subjects were much more likely to be younger at symptom onset and initial EGD (28 vs. 36 and 38 vs. 45, p < .05), to have SCE (53%, 36/68 vs. 17%, 5/29, p < .01) and smaller maximal (18.5 vs. 20, p< .01) and minimal esophageal mm diameters (13 vs. 14,p < .02 ) compared to PPI-REE patients ( Please see figure 1 below). Conclusion: Conclusion: When compared to PPI-REE, EoE patients are younger, have an earlier onset of symptoms, and have more advance esophageal stricture formation. Whether these findings represent a subtle pathophysiologic difference needs further exploration.Table 1: Positive Barium Swallow Variables