Anesthesia for the patients with mediastinal mass may be associated with significant respiratory and cardiovaacular complications due to compression of traeheobronchial trees, the pulmonary artery, heart and superior vena cava The authors present a case of a 6-year-old girl with a large mediastinal tumor located in anterior and superior mediaetinum. Preoperatively, the patient was asymptomatic and anesthesia was induced and maintained uneventfully. Operative finding was that 8 X 14 cm sized hemangioma was extended superiorly over thoracic outlet, posteriorly aorta and SVC, medially pericardium and right hilum and inferiorly right upper lung and pleura. Because difficulties in removal of the hemangioma were expected, exploratory thoracotomy was discontinued. On emergence, as soon as the patient was extubated due to irritability, the patient became cyanotic and was noticed bulging mass on right supraclavicular area, Intubation was attempted and during direct laryngoscopy, anesthesiologist also noticed a bulging mass in right oral cavity. Postoperatively, the patients airway was kept with endotracheal tube, but cyanosis appeared on the face and skin over the chest, but not below the abdomen. Bulging mass on right supraclavicular area, distension of neck vein and conjunctival edema were noticed only when the patient was crying or suctioned. Symptoms improved by deep sedation. We assumed that enlargement of hemangioma due to increased central blood volume occasionally compressed tracheobronchial tree and sup. vena cava when patient was irritable, crying and coughing. On 11th postoperative day, patient was transferred to the another hospital for the better treatment with endotracheal intubation.