The distribution of HLA class II (DR, DP, DQ) and Fc gamma R (I, II, III) was analyzed in the epithelia of patients with advanced marginal periodontitis using cryostat sections incubated with monoclonal antibodies (MoAb) against the Langerhans cell (LC) (CD1a) and various subtypes of HLA class II and Fc gamma R, and the indirect immunofluorescence technique. In the oral gingival epithelium (OGE), LC were concentrated subjacent to the connective tissue papillae, while in the pocket epithelium (PE), they were most abundant at the gingival margin. HLA-DP, DQ, and DR stained LC in both OGE and PE. HLA-DQ+ LC were significantly fewer than DP+ and DR+ LC. HLA-DR also stained keratinocytes (KC) in the whole extension of both OGE and PE. HLA-DP was also observed on KC, but not HLA-DQ. Fc gamma R II stained both LC and focal areas of KC. In PE FC gamma R II+ LC were concentrated near the bottom of the pocket, while in the OGE, they were concentrated at the gingival margin. Fc gamma R III was present only on KC, especially in the basal and suprabasal layer. The results indicate that the epithelial cells are actively involved in the development and maintenance of the inflammation of periodontal disease.