1. In this series of thirty-eight cases of osteoclastoma, twenty-five occurred at the end of a long bone. Nineteen were in the lower limb and half tif these were near the knee joint; six were in the upper limb; of the remainder, nine occurred in the vertebrae or the sacrum.

2. More cases occurred in females than males, the ratio being twenty-three females to fifteen males. Just over half the cases occurred in the second and third decades.

3. In seven there was a definite history of injury preceding symptoms by several months.

4. It is often difficult to arrive at a diagnosis on clinical and radiographic findings alone. Histological information is usually necessary before a certain diagnosis can be made. A limited biopsy is safe and reliable.

5. Malignant change with the development of metastases occurs in a small proportion of cases, regardless of the particular treatment that has been employed. This is illustrated in Case 3 of this series, in the case reported by Gordon Taylor, and in the case reported by Finch and Gleave.

6. The methods of treatment used in the patients here reported included curettage or local excision, with or without radiation, and radiation alone.

7. The patients treated by curettage or excision were dealt with during an earlier period than those treated by irradiation alone, and an exact comparison of results is not possible. The follow-up of patients treated by radiotherapy alone is too short to exclude the possibility of recurrence; but the immediate results appear to show definite improvement upon those of surgical treatment.

8. In this limited series it is to be noted that malignant change occurred in a higher proportion of cases treated by curettage and radiotherapy than in those treated by radiotherapy alone.

9. It appears that, in the treatment of osteoclastoma of bone, radiotherapy alone is the treatment of choice.