Sarcomas rarely follow irradiation of benign lesions of bone as the dangers of this form of therapy is well recognised. Forty-three patients with soft tissue neoplasms - mainly carcinoma - were irradiated and developed sarcomas in the radiation field. Twenty-four of these patients were seen at this centre in the last decade, a considerable increase compared to earlier years. Radiation osteitis may indicate the nature of the tumour but was only present in 50%. A purely lytic or purely sclerotic pattern was commoner than a mixed lytic and sclerotic appearance. CT scan, bone scan and angiography were helpful in delineating disease but did not assist in diagnosing the type of tumour. A tumour arising within the irradiated field is an indication for biopsy. Prognosis of radiation-induced sarcoma (RIS) remains poor, only five of the 43 patients survived 5 years.