Recognition of a moderately advanced cancer in the oral mucosa is not difficult provided the examiner can visualize the area. Most doctors and dentists will react appropriately when they see a lesion over 2 cm in diameter of an ulcerative or fungating nature. However, such prompt recognition frequently does not take place in early oral cancers, in those which are less than 1 cm in diameter, or in those which are in a stage prior to fungation or ulceration. The purpose of this presentation is to describe the clinical characteristics of the early oral cancer and to define it in histopathologic terms. In recent years, some clinicians have had the opportunity to see a significant number of such lesions and to develop a concept of the beginning of neoplasia in oral mucosa. Clinical Recognition.— Many oral cancers are found against a background of a basically abnormal mucosa, which may be