Adenoid cystic carcinoma is an uncommon histologic variant of adenocarcinoma which usuallyy arises from the salivary, lacrimal, or other exocrine glands. Characteristics of adenoid cystic carcinoma are its potential fo extending long distance submucosally and for perineural invasion. It grows slowly and may have a prolongec course before diagnosis and after treatment. Recently, we have experienced 2 cases of adenoid cystic carcinoma arising from main bronchus and trachea. One case was 58 years old female patient. Her symptoms were productive cough with dyspnea. She ha been history of shortness of breath, wheezing and cough during 4 years, which was initially diagnosed a bronchial asthma. The tumor was located on the left main stem bronchus which was obstructed the lumei nearly complete, by CT demonstration.