Mucoepidermoid tumors of the lung are extremely uncommon. Like the considerably more common mucoepidermoid tumors of the salivary glands, their histology is characterized by two components: a glandular mucoid element and an epidermoid element. The degree of malignancy is still a subject of discussion, but as with mucoepidermoid tumors of the salivary glands, mucoepidermoid carcinomas of the bronchus may be of either high or low-grade malignancy. The three cases reported here were of high-grade malignancy and metastasized irrespective of the degree of cellular differenciation. We have concluded that mucoepidermoid lung tumors should be considered as malignant lesions and the treatment has to consist in radical resection.