In eosinophilic esophagitis (EoE), the esophageal barrier integrity is impaired. Integrity can be assessed with different techniques. To assess the correlations between esophageal eosinophilia and various measures of mucosal integrity and to evaluate whether endoscopic impedance measurements can predict disease activity, endoscopies and mucosal integrity measurements were performed in adult EoE patients with active disease (≥15 eosinophils/high-power field) at baseline (n = 32) and 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. 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/high-power field) and these measurements were compared with 41 measurements of patients with active disease (at baseline or after failed treatment). All four 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 6,000 Ω·m with a sensitivity of 79% [95% confidence interval (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%). In EoE patients, markers of mucosal integrity correlate with esophageal eosinophilia. Additionally, endoscopic mucosal impedance measurements can predict disease activity.NEW & NOTEWORTHY In adult patients with eosinophilic esophagitis (EoE), the mucosal integrity, measured by making use of four different parameters, correlates strongly with esophageal eosinophilia. The accuracy of endoscopically measured mucosal impedance to distinguish active disease from remission was acceptable with moderate specificity and sensitivity. Mucosal impedance measurements can predict disease activity in adult EoE patients.