Cultured living human epidermal cells migrating on the surface of irradiated non-viable pig dermis, were found to produce bullous pemphigoid antigen at the epidermis-pig dermal junction between days 10 and 50 in culture. In certain series, the antigen was detected within the cytoplasm of the basal cells as well. These findings suggest that the bullous pemphigoid antigen is synthesized by epidermal cells.