Necrotizing fasciitis is an uncommon soft tissue infection, usually caused by toxin-producing virulent bacteria especially in mediastinum. It is characterized by widespread fascial necrosis primarily caused by Streptococcus hemolyticus characterized by necrosis of skin, subcutaneous tissues, fasciae, and muscles. It usually occurs in adults and is most often localized to the abdominal wall, the extremities, the perineum, the pelvis, and the thoracic region. Localization to the head and neck area is rarely encountered. Descending necrotising mediastinitis is a form of mediastinitis caused by odontogenic infection or deep cervical infections, which spreads to the mediastinum from the cervical fascial planes. Early diagnosis, prompt surgical drainage, monitoring of disease process, appropriate medical management in an intensive care unit and a multi-disciplinary approach can significantly reduces the mortality in this otherwise fatal condition.