1. One hundred and seven cases of Ewing's sarcoma have been studied.

2. The tumor is commonest in the second decade.

3. The innominate bone was the site predominantly affected. In long bones, contrary to the popular view, the mid-shaft was affected in less than 25 per cent of the patients.

4. The disease progresses rapidly. Pain and swelling are the cardinal features. Fever is often present.

5. Skeleton, lungs, lymph nodes, and other soft tissues are the site of metastases. More than 25 per cent of the patients had metastases either at the time of initial examination or by the time treatment was finished.

6. The roentgenographic appearance was variable. A mottled destruction of bone with a soft-tissue mass was the most constant finding. The onion-peel type of periosteal reaction was present in about 33 per cent of the patients and sun-ray spiculation in 10 per cent.

7. The diagnosis must always be verified histologically and aspiration biopsy is a very useful procedure.

8. Radiotherapy is the popular treatment. However, a survey of the literature shows that surgery appears to be the superior treatment when feasible. The role of chemotherapy is discussed. Since the over-all prognosis is poor, the selection of therapy remains an individual problem for each patient.

9. In the series reviewed, three patients lived more than five years (of sixty-six who qualified for a five-year assessment). In one of these patients a postradiation chondrosarcoma developed at the site of the original tumor.