Descending necrotizing mediastinitis is a rare disease that is usually caused by a spreading, diffuse inflammatory reaction (phlegmon) to an odontogenic infection or peritonsillar abscess. Reported mortality rates range from 25 to 40%. The use of antibiotics and advances in resuscitation procedures and critical care techniques have not essentially improved survival, and an effective treatment has not been clearly established. We report the findings of our 10-year study of 21 patients affected by phlegmon and/or fasciitis of the neck. The aim of our contribution is to help define the clinical criteria and diagnostic procedures that will improve the early diagnosis of mediastinal sepsis secondary to neck fasciitis and to suggest optimal treatment approaches. Our experience indicates that (1) cervical drainage alone is sufficient for cases of cervical phlegmon or mediastinal involvement that are limited to a single superior mediastinal space and (2) thoracotomy and drainage of mediastinal collections is necessary when mediastinal sepsis is more extensive.