['The purpose of this study is to examine the effect of insurance coverage on stage of presentation, treatment, and survival of head and neck cancer (HNC).', 'A retrospective study was conducted using the Surveillance, Epidemiology, and End Results (SEER) program to identify patients diagnosed with HNC. The primary variable of interest was insurance analyzed as a dichotomous variable: Patients were considered uninsured if they were classified as "uninsured" by SEER, whereas patients were considered insured if they were defined by SEER as "any Medicaid," "insured," or "insured/no specifics." The outcomes of interest were cancer stage at presentation (M0 vs M1), receipt of definitive treatment, and HNC-specific mortality (HNCSM). Multivariable logistic regression modeled the association between insurance status and stage at presentation, as well as between insurance status and receipt of definitive treatment, whereas HNCSM was modeled using Fine and Gray competing risks. Sensitivity logistic regression analysis was used to determine whether observed interactions remained significant by insurance type (privately insured, Medicaid, and uninsured).', 'Patients without medical insurance were more likely to present with metastatic cancer (adjusted odds ratio, 1.60; P < .001), were more likely to not receive definitive treatment (adjusted odds ratio, 1.64; P < .001), and had a higher risk of HNCSM (adjusted hazard ratio, 1.20; P\xa0= .002). Sensitivity analyses showed that when results were stratified by insurance type, significant interactions remained for uninsured patients and patients with Medicaid.'] Does health Insurance affect Head and Neck Cancer Treatment Patterns and Outcomes?