Benign soft-tissue neoplasms and tumorlike conditions of the musculoskeletal system are common. Sarcomas are less frequent, with only 5,000 new cases diagnosed each year in the United States. After plain radiographs of the affected area have been obtained, magnetic resonance (MR) imaging (both T1- and T2-weighted sequences) is the best imaging modality for detecting and characterizing the lesion. Although MR imaging is not specific in determining whether lesions are benign or malignant, it can be useful in evaluating other characteristics, such as size, pattern of growth, integrity of natural boundaries, and homogeneity. Biopsy must be done carefully, so as not to adversely affect the outcome. Technical considerations include proper location and orientation of the biopsy incision, meticulous hemostasis, and frozen-section analysis to ensure that diagnostic material has been obtained. Effective treatment requires close coordination between the surgeon, the radiation oncologist, the pathologist, the plastic surgeon, and the diagnostic radiologist. Limb-salvage surgery has resulted in a local control rate greater than 90%. High-grade tumors that are larger than 5 cm in diameter have the worst prognosis. The role of chemotherapy remains controversial and unresolved.