Langerhans cells (LC) serve as antigen presenting cells and provide immune surveillance within epithelia. Since depression of LC number and/or function may allow tolerance to antigens, we evaluated LC in median rhomboid glossitis (MRG), a condition linked to persistent candidal infection of lingual mucosa. Material included a total of 36 cases of MRG (7 of which did not show PAS+fungi) and 6 controls. LC were identified by their expression of S‐100 and HLA‐DR antigens and quantified using image analysis. Equal numbers of LC were identified using S‐100+ and HLA‐DR+ markers. The density of LC (cells/mm of basement membrane, mean±SD) in both PAS+ MRG (2.6±1.3) and PAS‐MRG (3.0±1.7) was markedly depressed compared with controls (17.2±6.4), (P<0.001). These findings indicate that the LC network is perturbed in MRG, and are consistent with the view that of localized defect in immune surveillance may contribute to persistent fungal infection of th