BACKGROUND: Bullous pemphigoid (BP) is a blistering disease associated with autoantibodies directed against two components of hemidesmosomes, BP180 and BP230. OBJECTIVES: To assess whether BP patients have autoantibodies targeting plectin, another hemidesmosomal component showing extensive homology to BP230. METHODS: Examination of sera from 16 patients with BP, using immunoprecipitation studies followed by immunoblotting. RESULTS: Serum of one of the 16 (6%) patients with BP contain autoantibodies binding to plectin, while no reactivity was found with sera from three control subjects. Sera from all 16 BP patients immunoprecipitated BP230 from extracts of biosynthetically radiolabelled human keratinocytes. CONCLUSIONS: Our results indicate that sera from BP patients might contain autoantibodies binding to plectin. Although this protein and BP230 are closely sequence-related, the occurrence of autoantibodies binding to plectin is a rare phenomenon in BP.