Deep neck infections present significant morbidity and mortality, particularly when associated with predisposing factors that impair a functional immunologic response. Familiarity with deep neck spaces and fascial planes is critical, because these form the basis for the emergent nature of the disease process. Common and potentially life-threatening complications include airway obstruction, jugular vein thrombosis, descending mediastinitis, sepsis, acute respiratory distress syndrome, and disseminated intravascular coagulation. The most common primary sources of deep neck infection are odontogenic, tonsillar, salivary gland, foreign body, and malignancy. Microbiology typically reveals mixed bacterial flora, including anaerobic species, that can rapidly progress to a fulminating necrotizing fasciitis. The treatment cornerstone remains securing the airway, providing efficient drainage and appropriate antibiotics, and improving immunologic status. A prolonged hospital stay should be anticipated.