In order to show the surface expression of Fc epsilon RI on human epidermal Langerhans cells (LC), we examined monomeric IgE binding to LC. We demonstrated that the majority of epidermal LC were able to bind monomeric IgE. IgE binding to LC could neither be prevented by preincubation of the tissue with monoclonal antibodies (mAb) against either Fc epsilon RII/CD23 or Fc gamma RII/CD32, nor by the addition of lactose, but could be entirely abrogated by preincubation with the anti-Fc epsilon RI mAb 15-1. These data show that epidermal LC express Fc epsilon RI molecules.