Herpes gestationis (HG) and bullous pemphigoid (BP) are blistering disorders with similar features, including urticarial lesions that progress to blisters and immunodeposition of C3 in a linear pattern at the basement membrane zone. Among their differences, HG is distinguished by its association with pregnancy, the puerperium, or hormonal perturbation. We describe the immunopathologic findings and clinical course in a multiparous woman with a severe blistering eruption. The patient was not pregnant. Malignancy evaluation was negative, and hormonal testing was normal. Histologic examination demonstrated a subepidermal bulla with eosinophils. Direct immunofluorescence showed C3 in a strong linear band at the dermal-epidermal junction. Indirect immunofluorescence demonstrated circulating IgG1 and IgG3 antibodies to basement membrane zone (epidermal component on salt-split skin), and complement-fixing IgG. Immunoprecipitation demonstrated antibodies to a 180-kd keratinocyte protein antigen. By clinical definition, this patient has BP. However, her disease presentation demonstrated features of both BP and HG. (J Am Acad Dermatol 1999;40:797-801.)