Abstract Since many dermatologic diseases affect the epidermal basement membrane zone, there has been intense investigation into the role of epidermal basement membrane zone constituents in various skin diseases, particularly subepidermal blistering skin diseases. The epidermal basement membrane zone consists of four major structural components—the basal cell plasma membrane, the lamina lucida, the lamina densa, and the sublamina densa zone, which contains anchoring fibrils. The lamina lucida is composed of laminin, bullous pemphigoid antigen (a disease-specific glycoprotein identified by antibodies circulating in patients' sera), and other as yet poorly defined antigens identified by in vivo bound and circulating antibodies in the sera of patients with herpes gestationis, scarring pemphigoid, and others. The lamina densa consists of type IV collagen and KF-1 antigen, which is noncollagenous and is identified by a skin-specific monoclonal antibody. The sublamina densa zone consists of AF-1 and AF-2 antigens and the epidermolysis bullosa acquisita antigen(s). Knowledge of the structure and chemical composition of the basement membrane zone is critical to an understanding of some of the genetic and immunologically mediated blistering skin diseases.