Two cases of familial benign chronic pemphigus (FBCP) are reported. The appearance of active lesions seemed to be related to trauma in one or to exacerbation of psoriatic lesions in another. Bacterial infection was not found to be an important factor in causing exacerbation of the disease. It is proposed that in genetically predisposed persons, histological or clinical manifestations of FBCP may become evident under stimulations such as trauma, bacterial infection, or dermatoses which serve to bring about a Köbner phenomenon.