Autoimmune bullous diseases are classified into pemphigus and pemphigoid. Pemphigus is designated as incurable disease by the Ministry of Health, Labor and Welfare, and it is said that pemphigus is difficult to care and can be fatal. The clinical course of bullous pemphigoid (BP) is better than that of pemphigus. However, as to the incidence of internal malignancies, it is well known that there is a significant difference between the two diseases. As the incidence of internal malignancies is high in BP, it is described in textbooks that patients with BP should be followed by a detailed screening for internal malignancies. We investigated the incidence of internal malignancies in 204 Japanese patients with autoimmune bullous disease who visited Tokai University Hospital in Kanagawa, Japan. We found that the incidence of internal malignancies was 11.2% in patients with pemphigus and 10.4% in patients with BP. Among pemphigus variants, the incidence was as high as 20% for pemphigus erythematosus. No relationship was found between malignancies and the severity of the autoimmune bullous diseases. Therefore it is clinically important to carry out a detailed screening for internal malignancies in patients with pemphigus as well as in patients with BP.