Mucoepidermoid carcinoma is a rare tumor of the lung that accounts for 0.1% to 0.2% of all pulmonary tumors. Herein we report our experience with a patient who suffered from bronchial mucoepidermoid carcinoma and 2-year left lung atelectasis. The tumor originated from the orifice of the left upper bronchus and obstructed the left main stem bronchus. A left upper sleeve lobectomy was performed and the remaining atelectatic lower lobe was fully expanded by 6 months postoperatively. The patient's pulmonary function significantly improved.