Background: In eosinophilic esophagitis (EoE) the esophageal barrier integrity is impaired. Integrity can be assessed with different techniques. Aims: To assess the correlations between esophageal eosinophilia and various measures of mucosal integrity, and to evaluate whether endoscopic impedance measurements can predict disease activity. Methods: Endoscopies and mucosal integrity measurements were performed in adult EoE patients with active disease (≥15 eosinophils/HPF) at baseline (n=32), after fluticasone (n=15) and elemental dietary treatment (n=14) and in controls (n=19). Mucosal integrity was evaluated during endoscopy using electrical tissue spectroscopy (ETIS) measuring mucosal impedance, and transepithelial electrical resistance (TER) and transepithelial molecule-flux through biopsy specimens in Ussing chambers. Results: We included 61 measurements; 32 of patients at baseline and 29 after treatment, 3 patients dropped-out. After treatment 20 patients were in remission (≤15 eosinophils/HPF) and these measurements were compared with 41 measurements of patients with active disease (at baseline or after failed treatment). All 4 mucosal integrity measures showed significant impairment in active EoE compared with remission. Eosinophilia was negatively correlated with ETIS and TER and positively with transepithelial molecule-flux (p≤0.001). The optimal ETIS cutoff to predict disease activity was 6000 (•m) with a sensitivity of 79% (95% CI 54 - 94%), specificity of 84% (95% CI 69 - 94%), positive predictive values of 89% (95% CI 77- 95%) and negative predictive values of 71% (95% CI 54 - 84%). Conclusions: In EoE patients, markers of mucosal integrity correlate with esophageal eosinophilia. Additionally, endoscopic mucosal impedance measurements can predict disease activity.