This article is only available in the PDF format. Download the PDF to view the article, as well as its associated figures and tables. Abstract This short book describes, clearly and comprehensively, Bowen's disease, erythroplasia of Queyrat, and all the in situ carcinomas found on mucous membranes. The history, cause, pathogenesis, clinical features, and histologic characteristics are reviewed with the help of a remarkable bibliography of 1,014 references. The authors support the theory that Bowen's disease is the most common form of in situ epithelioma of the skin and mucous membranes. They consider that erythroplasia of Queyrat is Bowen's disease of the glans penis. They also describe involvement of various sites, ie, the vulva; vagina; uterine cervix; anus; eye; buccal, pharyngeal, and nasal mucosa; and larynx. The authors greatly extend the concept of Bowen's disease as they propose that in situ carcinoma of the bronchial tract, esophagus, stomach, rectum, urinary tract, breast, and ovary is similar to Bowen's disease, since it has the same histogenesis. This enlargement of the concept of Bowen's disease will certainly