Mediastinal and thoracic extension of head and neck infections are rare but occur even in the modern antibiotic era. Early intervention is paramount to successful clinical outcome. 111Indium-labeled white blood cell (WBC) scan, a new imaging modality, appears to play a role in complementing computed tomographic (CT) findings, demonstrating early extension of disease, and following therapeutic efficacy. Together, the CT scan and WBC scan aid in directing early intervention and extent of surgery in this disease of high-potential mortality. We report 3 cases of deep head and neck infection complicated by mediastinal extension, including mediastinitis, pericardial effusion, and tamponade, empyema, and respiratory failure. Early surgical intervention included neck drainage, tracheostomy, thoracotomy, and pericardiotomy. While usually associated with greater than 50% mortality, all of the patients in this series survived. Based on our experience, we recommend prompt aggressive surgical debridement in treating mediastinal complications resulting from head and neck infections.