There have been several reports in the literature of coexistent psoriasis and bullous pemphigoid. In most cases, the bullous pemphigoid lesions have been considered to be induced by antipsoriatic treatments. We describe a patient with psoriasis in whom bullous pemphigoid developed during psoriasis treatment, but the exact etiologic factor was not identified. Recently, some reports have suggested that an immunologic or biochemical association between the two diseases plays a role in the pathogenesis.