A review was made of the morphologic features of cells aspirated from 17 sarcomas (5 malignant fibrous histiocytomas, 3 fibrosarcomas, 3 leiomyosarcomas, 3 endometrial stromal sarcomas, 1 osteosarcoma and 2 poorly differentiated sarcomas) metastatic to the lung, paying particular attention to the morphologic differences between the cells of sarcoma and carcinoma and between the cells of the different types of sarcoma. In general, sarcomas were characterized by loosely cohesive, rather flat, cellular aggregates and isolated cells. Three-dimensional cell balls or clusters were not present in any case. Cellular pleomorphism was a common, though not invariable, feature. Each type of sarcoma showed some morphologic distinctiveness; however, certain morphologic features were common to more than one type of sarcoma. By comparing the cytologic features of metastatic sarcomas in aspirates with the histologic features of the primary neoplasms, it should usually be possible to decide if a pulmonary lesion is a metastatic sarcoma.