Primary Pulmonary leiomyosarcomas are rare tumors. These tumors may arise at any level of the lung in which smooth muscle fibers are found. The highest incidence of sarcoma is during the fourth decade whereas for bronchogenic carcinoma the maximum incidence is during the sixth and seventh decades. Leiomyosarcomas are aggressive and progressive. Treatment is mainly surgical. The chemotherapy is ineffective and the effectiveness of radiotherapy depends on the total dose of irradiation. Prognosis and significant survival rate are related to the size of the lesion. We report one patient with primary pulmonary leiomyosarcoma involving the right lower lung.