Computed tomography examinations were performed on 74 patients who presented to the Children's Hospital of Philadelphia and the Hospital of the University of Pennsylvania with a known or suspected diagnosis of primary or secondary soft tissue sarcoma. Focal masses were detected on computed tomography study in 59 patients. These masses were classified into three broad categories: centrally necrotic masses with a large predominantly liquefactive center and higher density periphery (29); multilocular, septated masses with distinct linear bands or striations (21); and miscellaneous masses (9). The miscellaneous category included six inhomogeneous and three homogeneous masses. The apparent density differences within these sarcomas were best appreciated on dynamic postcontrast scans. The computed tomography appearance of these sarcomas may be explained by the pathologic findings of cystic degeneration, extensive necrosis, central cavitation, focal hemorrhage, and myxoid changes.