Conjunctival biopsy specimens from 13 patients with cicatricial pemphigoid and from 13 age-matched healthy individuals undergoing cataract surgery were analyzed by light microscopy and immunohistochemical techniques, including a panel of monoclonal antibodies used to characterize inflammatory mononuclear cell phenotypes. Results of histologic examination of cicatricial pemphigoid specimens showed typical squamous metaplasia, vasculopathy, increased numbers of mast cells, and abundant plasma cells. All cicatricial pemphigoid specimens demonstrated immunoreactants at the epithelial basement membrane zone (BMZ). Epithelium of cicatricial pemphigoid conjunctiva showed significantly more T-helper cells (CD4+), dendritic cells (CD1+), and macrophages (CD14+), and a significantly higher helper/suppressor ratio than did controls. In the substantia propria, pemphigoid specimens showed dramatically increased inflammatory infiltrate with significantly more cells staining, in order of frequency, for T cells (CD3+, CD5+), T-helper cells (CD4+), T-suppressor cells (CD8+), macrophages (CD14+, Mac-1+), and dendritic cells (CD1+, HLA-DR+). Ten percent of these cells expressed interleukin-2 receptor protein (CD25+), indicating T-cell activation.