Descending necrotizing mediastinitis (DNM) is defined as mediastinal infection that begins at the cervical region and spread through deep fascial planes into the mediastinum. This is a rare and life-threatening complication of deep neck space infection. As infection reaches the mediastinum, widespread cellulitis, necrosis, abscess formation and sepsis may occur. So, early diagnosis and immediate antibiotics and surgical treatment are required to improve the poor prognosis of DNM. We present four cases of deep neck infection causing a virulent mediastinitis with a literature review.