Objective — to identify filiform papillary lesions, localization changes, and the composition of the microflora of the dorsal lingual surface in patients with gastroesophageal reflux disease (GERD). Subject and methods. Dorsal lingual surface biopsy specimens were investigated in 7 patients with GERD (3 men, 4 women) and in 6 individuals without digestive diseases (3 men, 3 women). The diagnosis of GERD was based on a set of clinical data, daily pH-metry, EGDS, and the specialized GerdQ questionnaire. Scanning electron microscopy and fluorescence confocal microscopy were used. Results. Intact filiform lingual papillae had a complex structure and consisted of primary and secondary papillae. Foci of increased epithelial desquamation with partial or complete loss of secondary papillae were detected in patients with GERD. There was a microflora biofilm only on the epithelium of the secondary papillae in the intact areas and in the areas with preserved secondary papillae in patients with GERD. On the contrary, the foci of lesion and those with completely lost secondary papillae in GERD patients exhibited the microflora (more diverse in its morphological characteristics) on the surface of the epithelial cells of primary papillae, except for their cup-shaped hollows in the area of the lost secondary processes. These cup-shaped hollows preserved dense intercellular contacts of epithelial cells. Conclusion. The lingual mucosal filiform papillae in GERD patients are characterized by the appearance of areas with partial or complete loss of secondary papillae and with increased desquamation of epithelial cells. There is microflora biofilm translocation to the primary papillae, except for their cup-shaped hollows (an area of the lost secondary papillae). Translocation of the microflora increased its morphological diversity.