Anti-p200 pemphigoid and anti-laminin 5 mucous membrane pemphigoid are two distinct autoimmune blistering skin diseases. Patients with anti-p200 pemphigoid demonstrate circulating autoantibodies to an unknown 200-kd acidic noncollagenous glycoprotein of the lower lamina lucida, whereas anti-laminin 5 mucous membrane pemphigoid is characterized by an autoimmune response against the major basement membrane adhesion molecule laminin 5. In this report, we describe a patient who developed a recurrent nonscarring blistering eruption, affecting both skin and mucous membranes. Immunoblotting of dermal extracts and extracellular matrix of cultured keratinocytes revealed circulating autoantibodies directed to the p200 antigen and the alpha3 chain of laminin 5, respectively. The unusual clinical and immunologic profile of this case suggests that molecular specificity of circulating autoantibodies affects the clinical presentation of autoimmune subepidermal blistering skin diseases.