Edema, rings, exudates, furrows, and strictures (EREFS) represent the major endoscopic features of eosinophilic esophagitis (EoE). The Endoscopic Reference System (EREFS) grading system is easy to learn and apply during daily clinical practice in the diagnosis and follow-up of EoE patients. When endoscopy is performed by an EoE-experienced physician, the EREFS criteria will identify the majority of EoE patients. The EREFS score from the area of greatest involvement of the esophagus should be reported. The EREFS grading system was formally validated as an endoscopy score and several randomized placebo-controlled trials have shown responsiveness of the EREFS score to therapeutic interventions.