Mucoepidermoid carcinoma developed in tracheobronchjal tree is one of rare lung tumor. It is histologically divided into low grade malignancy of relatively benign course versus high grade malignancy of fatal course. In low grade malignancy, it can be curative with a surgical resection. We experienced a case of mucoepidermoid carcinoma in a 28-year-old woman who complained sudden dyspnea and presented right total lung collapse on chest roentgenogram. It was diagnesed as a low grade mucoepidermoid carcinoma and removed by the surgical excision.