We report a case of mucoepidermoid carcinoma of the trachea in a 23-year-old pregnant female in her 39th week. The patient had cough and wheezing in the early morning for 9 months before admission. No abnormalities were detected on a chest roentgenogram. At Caesarean section, fiberscopy revealed a polypoid lesion narrowing the trachea. The pathologic diagnosis made from the biopsy specimen obtained was low-grade mucoepidermoid carcinoma and the lesion was resected. Airway hyperresponsiveness was shown before resection with airflow limitation, however, airway reactivity and airflow limitation improved 1 year after resection.