Epidermal dendritic cells of normal adult foreskin, and of lesional skin from patients with atopic eczema, stasis eczema and urticaria pigmentosa are shown to be highly reactive with two different monoclonal antibodies (29C6 and 6F7) specific for extracellular domains of the alpha-chain of the high-affinity IgE receptor. By their distribution pattern, the reactive cells are Langerhans cells. This is confirmed by immunoelectron microscopic demonstration of Birbeck granules in the labelled epidermal cells. Very weak staining is observed on the same cells with an antibody (Tü1) against the low-affinity IgE receptor. Pre-incubation of the sections with IgE partially blocks binding of 6F7 antibody. Langerhans cells, together with dermal mast cells, can therefore bind IgE with high efficiency, and may in this way participate in IgE-mediated cutaneous diseases.