A 3-year-old girl was evaluated for persistent middle lobe atelectasis. Fiberoptic bronchoscopy revealed a spherical mass occupying the middle-lobe bronchus. The biopsy specimen disclosed a low-grade mucoepidermoid carcinoma. A lobectomy was performed. The patient is in good condition 2 years after the operation. Mucoepidermoid tumors are rare bronchial adenomas comprising 1% of all lung neoplasms. Children are very infrequently affected. The clinical behavior of these tumors is controversial. Surgical resection of the low-grade-type tumor has an excellent prognosis.