Since the discovery of autoantibodies in patients with pemphigus, pemphigus has been intensively studied by dermatologists and cutaneous or cellular biologists by means of various techniques including immunofluorescence, immunoelectron microscopy, immunoprecipitation, immunoblotting, and molecular biology. In this article, up-dated topics on pemphigus obtained by each individual technique are reviewed. In the course of immunofluorescence studies on unusual cases of blistering diseases, a new entity characterized by immunoglobulin A (IgA)-type autoantibodies directed against keratinocyte cell surfaces has been discovered. Immunoelectron microscopy using low temperature post-embedding gold labeling enabled us to quantitate binding sites of pemphigus autoantibodies within desmosomes at different levels of epidermis. Immunoprecipitation and immunoblot analyses allowed us to characterize antigen complexes in paraneoplastic pemphigus. Finally, approaches using molecular biology not only have given us a fundamental insight that pemphigus autoantigen is a cadherin-type cell adhesion molecule both in pemphigus vulgaris and pemphigus foliaceus, but also provided tools to develop novel diagnostic and therapeutic strategies.