Patients often present to the emergency department with a wide variety of nontraumatic infectious, inflammatory, and neoplastic conditions of the head and neck. Because the use of cervical and neck computed tomography (CT) has become routine in the emergency setting, knowledge of the imaging findings of common acute conditions of the head and neck is essential to ensure an accurate diagnosis of these potentially life-threatening conditions, which include oral cavity infections, tonsillitis and peritonsillar abscess, sialadenitis, parotiditis, diskitis, thrombophlebitis, periorbital and orbital cellulitis, infectious cervical lymphadenopathy, and various neoplasms. Less common conditions that require rapid diagnosis and treatment include epiglottitis, invasive fungal sinusitis, angioedema, and deep neck abscess. Familiarity with these conditions enables the radiologist to make a prompt diagnosis, assess the extent of disease, and evaluate for potential complications. CT is the first-line imaging modality in the emergency setting; however, magnetic resonance imaging plays an important secondary role.