In the present study a comparative immunohistochemical study was performed on skin biopsies from of patients with Jessner's lymphocytic infiltration of the skin (LIS), polymorphous light eruption (PLE), discoid lupus erythematosus (DLE) and sub‐acute cutaneous lupus erythematosus (SCLE) using a large panel of monoclonal antibodies against T cell differentiation antigens (CD3, CD4, CDS), immunoregulatory T cell subsets (CD7, 4B4, 0H4, Leu 8), B cells (CD22), activated cells CD25, OKT9, HLA‐DR), Langerhans cells (CD1) and macrophages (Leu‐M5). The results showed many similarities between LIS and PLE. The most important differences between these conditions and CDLE/SCLE were the high proportions of cells reactive with monoclonal antibody Leu‐8 and the absence of T cells expressing HLA‐DR antigens in LIS and PLE, suggesting absence of local T cell activation in these conditions. The differential diagnostic and pathogenetic aspects of these findings will be