Abstract: Lichen planus erythematosus (LPE) is one of the most common and clinically manifest skin and mucosal dermatoses. According to different authors, the population frequency of LPE (0.4-1.9%) varies in different regions of the world and the proportion to other dermatoses. An important obstacle to the study of the epidemiology of LPE is the significant differences not only in the frequency of patients ‘ visits to dentists and dermatologists, but also in the assessment of the frequency of combined lesions of the oral mucosa and skin by both dentists and dermatologists.