Rackground - Thoracic sarcomas, either primary or secondary, are rare. As compared with the conventional radiography that is often rather nonspecific, computed tomography (CT) is very useful in their differential diagnosis. The purpose of this presentation is to demonstrate the typical and some unusual CT manifestations of live types of thoracic sarcoma. Methods - Two cases each of five types of thoracic sarcomas were selected from our file collected over the past ten years. Their chest radiographs and thoracic CT were reviewed. Results - Osteosarcomas were characterized by a tumor mass with various degree of calcification or ossification. A low-grade primary chondrosarcoma of the sternum with 'snowstorm' calcification and a high- grade metastatic chondrosarcoma with scanty puncture calcifications were demonstrated. Expansion of bone shaft with subperiosteal bone formation was seen in a primary Ewing's sarcoma of a rib, while a Ewing's sarcoma metastatic to the lung and pleura showed a homogeneous opacity resembling a high density effusion. Two rare primary pulmonary leiomyosarcomas, one with homogeneous round opacity while the other with irregular heterogeneous radiodensity were described. Primary pulmonary angiosarcoma usually presents an multiple pulmonary nodules, but the case demonstrated here showed a solitary lobulated mass with heterogeneous density. Linear infiltrates along the bronchovascular bundles were most characteristic of AIDS-related Kaposi's sarcoma. Conclusions - Thoracic CT were usually quite characteristic and highly suggestive of specific types of primary or metastatic thoracic sarcoma such an osteosarcoma, chondrosarcoma, Ewing's sarcoma, leiomyosarcoma, and malignant vascular tumor. However, unusual manifestations could sometimes be encountered, as illustrated in this report.