Abstract. The problem of diseases of the oral mucosa covers a wide range of issues. Despite numerous studies, etiology, pathogenesis, clinical presentation, treatment of this pathology is not fully permitted. The current most widely used medical term is "recurrent aphthous stomatitis" or simply "aphthous stomatitis". Historically, many different terms have been used to refer to recurrent aphthous stomatitis or its sub-types, and some are still in use. Synonyms for major RAS include Sutton's ulcers (named after Richard Lightburn Sutton), Sutton's disease, Sutton's syndrome and pariadenitis mucosa necrotica recurrens. The incidence of the disease ranges from 10 to 40%, according to WHO, 20% of the population is affected. Currently, the etiology and pathogenesis of this disease are not fully established and, despite the variety of studies conducted in our country and abroad, remain the subject of numerous discussions. Microscopic and histological studies of the " Denta Aloe" preparation were carried out in the histological laboratories of the Republican Pathological Center, the staining of the micropreparations was performed using hematoxylin and eosin dyes.