Primary pulmonary sarcomas are rare tumors. Because the lung is one of the favored metastatic sites for soft tissue sarcomas, care must be taken when evaluating these lesions to rule out the possibility of an alternate primary source by means of thorough clinical history and radiographic evaluation. In addition to the difficulties involved in separating primary from metastatic tumors, pulmonary sarcomas must be distinguished from a number of sarcomalike primary lung neoplasms, including spindle and giant cell (pleomorphic) carcinoma, and from mixed epithelial/mesenchymal lesions such as pulmonary blastoma and carcinosarcoma. The criteria helpful for accomplishing this distinction are discussed, along with a review of primary sarcomas of the lung, with emphasis on clinicopathologic, immunohistochemical, and ultrastructural features that may be of aid for diagnosis. Additionally, recent or newly described entities are also discussed, and evolving concepts on the pathogenesis and terminology of these lesions are underscored.