Cell infiltrates in the dermis of biopsy specimens from skin lesions of seven patients with scabies were characterized by receptors for sheep erythrocytes (T-lymphocytes), Fc C3b (macrophages and B-lymphocytes) and C3d receptors (B-lymphocytes) using hemadsorption to cryostat sections in closed chamber. T-lymphocytes were also identified using an indirect immunofluorescence technique with rabbit anti-T-lymphocyte serum. All sections showed perivascular mononuclear cell infiltrates in the dermis as judged by sections stained by hematoxylin and eosin. T-lymphocytes were the predominant cells in the infiltrates. Fewer macrophages and very few B-lymphocytes were detected. Cell-mediated immune response may be of importance in the pathogenesis of scabies.