Pemphigoid diseases are a group of well defi ned autoimmune disorders that are characterised by autoantibodies against structural proteins of the dermal-epidermal junction and, clinically, by tense blisters and erosions on skin or mucous membranes close to the skin surface. The most common of these diseases is bullous pemphigoid, which mainly aff ects older people and the reported incidence of which in Europe has more than doubled in the past decade. Prognosis and treatments vary substantially between the diff erent disorders and, since clinical criteria are usually not suffi cient, direct immunofl uorescence microscopy of a perilesional biopsy specimen or serological tests are needed for exact diagnosis. In eight pemphigoid diseases the target antigens have been identifi ed molecularly, which has allowed the development of standard diagnostic assays for detection of serum autoantibodies-some of which are commercially available. In this Seminar we discuss the clinical range, diagnostic criteria, diagnostic assay systems, and treatment options for this group of diseases.