Over a 25-year period we have treated 36 patients with osteosarcoma of the pelvis. Of the tumours, 24 (67%) were primary osteosarcomas and 12 (33%) arose either after irradiation or in association with Paget's disease. Six patients had a hindquarter amputation and 12 were treated by a limb-salvage procedure with intrapelvic excision. The five-year survival rate of all the patients with pelvic osteosarcoma was 18%, while for 17 treated by chemotherapy and surgery it was 41%. The prognosis for patients presenting with metastases or with secondary osteosarcoma was appalling and none survived after 29 months. No patient over the age of 50 years when seen initially survived for a year. Youth and a good response to chemotherapy along with complete surgical excision offer the best chance of cure.