Epidermolysis bullosa acquisita (EBA) is a rare non hereditary bullous disease. One case is described with a morphological, and immunocytochemical ultrastructural study. The plain ultrastructural morphology showed a dense amorphous deposit in the superficial dermis, under the basal lamina. Immunofluorescence showed IgG and C3 deposits. The ultrastructural study (direct immunoperoxidase technique using Fab) showed a dense labelling associating : dark dots spaced under the basal lamina and fogging less dense labelling in the clarified superficial dermis. Using the patient's antibodies an indirect reaction on normal human skin performed : the same dotted sub laminal labelling was found but with no dermal diffuse reaction product. The study shows the site and the aspect of the Ig deposit in EBA and indicates that the antibodies demonstrated in some patients are reactive with a constituent of the normal superficial dermis.