Pulmonary artery leiomyosarcomas are rare tumors. They cause symptoms suggestive of recurrent pulmonary emboli. As in the case reported here, the diagnosis is virtually never considered initially, despite modern diagnostic imaging methods, but usually made at autopsy or at histologic examination of material removed from the pulmonary artery at surgery. The prognosis remains poor and prolongation of life up to 6 months has not been clearly demonstrated with radical excision in conjunction with radiotherapy. The difficulty is the accurate diagnosis required to consider these tumors for curative resection, which is the only hope for a longer disease-free course.