Congenital choanal atresia is the developmental failure of one or both posterior nasal cavities to communicate normally with nasopharynx. Coexisting congenital anomalies are present 20 to 50% of patients in most series. The newborn is enable to breathe through the nose and mouth breathing is an acquired habits. Most infants can be obtained to mouth breathing in 3~4 or more weeks. Infants will be suffocated if the nasal airway is totally obstructed. Bilateral choanal atresia presents as an neonate emergency condition to avoid asphyxia and to establish a feeding pattern. It is urgently necessary to obtain a satisfactory nasal airway. However, unilateral choanal atresia is usually recognized in childhood and requires an elective, safe operative technique with minimal morbidity and predictable long term result. The authors have experienced one case of unilateral congenital choanal atresia with good result by transpalatal approach.