1. Drinkers and cigarette smokers are at very high risk for the development of upper aerodigestive tract and lung squamous carcinomas. 2. The floor of the mouth, the ventrolateral tongue, and the soft palate are high-risk sites within the oral cavity and oropharynx. 3. Mucosal erythroplasia rather than leukoplakia is the earliest visual sign of oral and pharyngeal carcinomas. 4. Areas of mucosal abnormality, especially redness or inflammation in high-risk sites, that persist for more than 14 days without obvious etiology or resolution should be biopsied. 5. Asymptomatic, erythroplastic lesions should not be regarded merely as precancerous changes. The evidence indicates that these lesions in high-risk sites should be considered to be invasive carcinoma or at the very least carcinoma in situ, unless proven otherwise by biopsy. 6. Toluidine blue staining is a useful diagnostic adjunct, particularly as a method of ruling out false-negative clinical impressions. It may also be used as a screening rinse in high-risk patients to encompass the entire oral mucosa after a negative clinical examination and as a guide to improve biopsy yields. 7. If oral or pharyngeal cancer is identified, evaluations of the larynx, hypopharynx, esophagus, and lungs should be performed to rule out second primary cancers. Yearly aerodigestive surveillance should be continued after satisfactory treatment of the index cancer.