A case of pulmonary leiomyosarcoma originating in the left pulmonary artery stem in a 28-year-old Japanese man is reported. The patient complained of recurrent hemoptysis. The diagnosis was made at exploratory thoracotomy. Two days following thoracotomy, under cardio-pulmonary bypass, the upper one-third of the pulmonary trunk and part of the right pulmonary artery stem were resected and left pneumonectomy was performed. A Dacron prosthetic 23 mm composite graft was inserted to replace the pulmonary trunk and a portion of the right pulmonary artery. Postoperative course was uneventful. The patient died about 8 months after surgery because of right lung metastases. In our review of surgically treated forty-eight cases, complete resection was performed in 11, incomplete resection in 23, and embolectomy in 6, whereas 8 were unresectable. A localisation often not allowing adequate resection of the tumor or the advanced stage of the tumor at surgery are considered the main causes of the poor prognosis of the pulmonary sarcoma.