ABSTRACTThe purpose of the present study was to examine the phenotype of cutaneous immunocompetent cells and to quantify Langerhans cells in Lichen planus by the use of monoclonal antibodies directed against T‐cell populations.Helper cells (OKT4+) and Suppressor/cytotoxic cells (OKT8+) were observed in all cutaneous infiltrates, and numerous Langerhans cells were identified by OKT6, BL6, and BL2 (HLA‐DR) in the epidermis and dermis.The quantification of Langerhans cells demonstrated that the number of dendritic cells in epidermis is greater in involved skin than in non‐involved skin. In recent lesions, Langerhans cells are more abundant than in older lesions.The results in peripheral blood indicated a T Helper/Suppressor imbalance with a decreased T‐Suppressor/cytotoxic subpopulation in patients with lichen planus diseases.In lichen planus, our results suggest an immunological reaction involving all the immunocompetent cell subpopulations with a first stage of information by Langerhans cells (OKT6+, BL6+, BL2+ (HLA‐DR)) and Helper cells (OKT4+), and second stage mediated by Suppressor/cytotoxic cell