Life threatening mediastinitis as a complication of acute epiglottitis is very rare. A 38-year-old male in previously good health was admitted to our hospital in a state of unconsciousness. Seven days prior to admission he had complained of a sore throat, dysphagia, high fever and dyspnea. A chest X-ray on admission showed widening of the mediastinum, mediastinal emphysema, subcutaneous emphysema and left pleural effusion. Bronchoscopy showed the swelling of supraglottic structures. He was diagnosed as having acute mediastinitis and pyothorax as a complication of acute epiglottitis, but pathogens were not identified. The blood was hyperglycemic and insulin therapy was started. Though he gradually improved by massive antibiotic therapy, steroid therapy, tracheotomy and surgical drainage of both the left thoracic cavity and the mediastinum, he died suddenly of massive hemoptysis. Autopsy revealed that the acute mediastinitis had healed, but that the Aspergillus infection was present in both lungs and the pericardium. The Aspergillus infection was not lethal in the present case, and it seemed that death had resulted from arterial hemorrhage caused by erosion of the trachea. The present case suggests the need for antifungal therapy even in non-immunocompromised patients in particular when massive doses of antibiotics and steroids are administered.