Primary leiomyosarcoma is an extremely rare tumor. We exprienced a case of 46-year-old man with a mass located in the left upper lobe bronchus which was discovered on a chest CT. Cytology of the sputum and bronchoscopic biopses did not reveal any malignant cells. The patient underwent a left sleeve upper lobectomy. The tumor was growing from the left upper lobe bronchus and had partially destroyed the lung parenchyme. The pathologic feature of the tumor was composed of fascicular arrayed cellular spindle cells with blunt-ended nuclei revealed mild to moderate pleomorphism and frequent mitoses (15/10HPF). The immunohistochemical staining was revealed positive reaction for antibody to smooth muscle actin and desmin. We conclude that the tumor is leiomyosarcoma of the lung and then report with a review of the literatures.