We studied the relation between occupation and oral and pharyngeal cancer with a population-based case-control study conducted in four areas of the United States. The study group included 1,114 incident male and female cases and 1,268 frequency-matched controls. After adjustment for age, race, smoking, alcohol, and study location, an analysis of lifetime occupational histories revealed a small number of noteworthy associations. Risk was increased among male carpet installers (23 cases, 4 controls), with an adjusted odds ratio of 7.7 [95% confidence interval (CI) = 2.4-24.9], and tended to rise with longer duration of employment. A decreased risk was found among male and female textile mill workers (odds ratio 0.48, 95% CI = 0.27-0.88). Previously reported increases in oral cancer risks among printing workers, electrical and electronics workers, and workers other than carpet installers who were possibly exposed to formaldehyde were not found in this study. For several employment groups, including male machinists, primary metal industry workers, petroleum industry workers, painters, furniture and fixture industry workers, woodworking machine operators, and workers with inferred exposure to fossil fuel combustion, odds ratios were approximately 2.0 for cancers of pharyngeal sites.