The paper contains the results of clinical and morphofunctional examinations of a patient with eosinophilic esophagitis complicated by esophageal stenosis and detected in the presence of controlled mild persistent asthma and food allergy. The endoscopic and morphological diagnostic criteria pathognomonic for this disease have been confirmed. The immunohistochemical study of esophageal mucosal biopsy specimens revealed the specific features of the composition of an infiltrate, which account for the early development of fibrosis and permit eosinophilic esophagitis to be referred to as special immunocompetent diseases.