One in three adults in the United States smokes. Smokers inhale one quarter of the smoke from cigarettes. But 75% of cigarette smoke is released into the environment. Nonsmokers are exposed to this environmental tobacco smoke and are at risk for disease. A growing body of literature supports the association of passive, involuntary, or secondhand smoking with human pathology. This discussion examines the makeup of environmental tobacco smoke and its role in causing human disease with a review of the literature relating environmental tobacco smoke to head and neck pathology.