Primary pulmonary artery sarcomas are uncommon neoplasms with up to 20% of cases being leiomyosarcomas. In many instances, the diagnosis is difficult and delayed. We report the case of a 75-year-old male who presented with symptoms suggestive of recurrent pulmonary thromboemboli, in which a primary leiomyosarcoma of the pulmonary artery was successfully removed surgically. Three years after surgery, the patient is well and with no evidence of recurrence or metastatic disease.