Significant differences exist between neonatal and adult airways. Anesthetic management of the airway may be challenging in neonate and young infant with large neck mass because these patients are at risk for sudden complete airway occlusion resulting in hypoventilation and hypoxemia. We experienced a 30-day-old baby presented with large cystic hygroma on the left side of neck. This mass was infiltrated in pharynx and large enough to disturb swallowing and breathing, and was not reduced despite of sclero-therapy. Therefore he was decided to get surgical removal. During the gaseous induction with sevoflurane, spontaneous respiration was maintained because difficulty was encountered with intubation. Intraoperatively, the endotracheal tube was dislodged unexpectedly because vigorous surgical traction. Postoperatively the baby was extubated 2 day after operation, and suffered from transient facial nerve palsy and continuous discharge from surgical wound. He was administered ICU for a long time.