An examination of the oral cavity and oropharynx in asymptomatic patients at high risk requires an orderly visual inspection of the entire oral and oropharyngeal mucosa with particular attention to the tongue, floor of mouth, soft palate, uvula, tonsillar pillars, and the lingual aspects of the retromolar trigones. Completion and clear documentation of the entire examination should be recorded. Detected lesions that do not resolve in a reasonable length of time--two to three weeks--require intense and assiduous investigation. The following specifics should be considered. 1. Alcohol drinkers and cigarette smokers, especially those 40 years of age and older, 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 complex are the high-risk sites within the oral cavity and oropharynx. 3. Persistent mucosal erythroplasia rather than leukoplakia is the earliest visual sign of oral and oropharyngeal carcinoma. These 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 carcinoma in situ unless proven otherwise by biopsy. 4. 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 rinse in high-risk patients to encompass the entire oral mucosa after a negative clinical examination and as a guide to improve biopsy yields. 5. If oral or oropharyngeal cancer is identified, evaluations of the larynx, hypopharynx, esophagus, and lungs should be performed to rule out multiple primary cancers.(ABSTRACT TRUNCATED AT 250 WORDS)