We describe a patient with coexistent dermatomyositis and bullous pemphigoid; both appeared within a few weeks. Protein blotting showed binding of the patient's serum to the classic 220 kd bullous pemphigoid antigen. Because of the close temporal association of the two disorders, we believe that they are almost certainly etiologically linked. One possibility is that exposure of basement membrane antigens by dermatomyositis led to exposure of bullous pemphigoid antigen and subsequent antibody formation.