The pathology of eosinophilic esophagitis (EE) when fully developed in humans is highly characteristic and readily discriminated from the histology of the normal esophagus. The histologic alterations are not pathognomonic for any of the multiple causes of EE, and the correct diagnosis can be made only if the histology is correlated with clinical findings. The histology of the normal esophagus is reviewed and contrasted with the findings in EE. The characteristic findings in EE are illustrated. Selected research in humans and animal models pertinent to EE are briefly reviewed.