The clinical records and histologic material of 48 patients with extraosseous osteogenic sarcoma were reviewed. Most patients developed their tumors in the fifth or sixth decades of life. Five patients (10%) developed neoplasms in an area of prior radiation therapy, a median of 15 years after their exposure. Six patients (13%) related a history of trauma to the area where their extraosseous osteogenic sarcoma developed. The course of most patients was that of multiple local recurrences (69%) followed by pulmonary metastases (80%) and death (76%). Amputation or wide resection followed by irradiation appeared to be the most effective types of therapy, with median survivals greater than 60 months for patients receiving these treatments, compared to 28 months for patients initially treated with resection alone. Chemotherapy was not effective for patients with advanced disease; however, adjuvant chemotherapy after surgery may have been of value. Four of five patients who received adjuvant chemotherapy after surgery are alive and disease-free; the only two survivors after development of pulmonary metastases received adjuvant chemotherapy after surgical resection of visible pulmonary metastases.