A rare case of descending necrotizing mediastinitis (DNM) secondary to a nontraumatic retropharyngeal abscess is reported. Even in the era of antibiotics, the mortality of DNM is still around 40%. In spite of drainage of a localized neck abscess, and the administration of systemic antibiotics, the retropharyngeal abscess extended to the pericardial and pleural cavities. Several drainage procedures and thoracotomies were performed to treat the bilateral empyemas and purulent pericarditis. The patient was discharged on hospital day 52. Computed tomography was used to follow the progression of disease, and assess the efficacy of treatment. DNM is a very aggressive form of mediastinitis. The importance of proper mediastinal drainage, as well as the systemic administration of antibiotics, must be emphasized.