Abstract Twenty - two patients with Giant cell tumor of bone(GCT) were treated with radiation therapy from 1970 to 1993 in our department. Three patients were treated by means of radiotherapy alone

fourteen patients by both radiotherapy and surgery. The remaining 5 were treated with radiation when they had a relapse after operation. The tumor doses were less than 40 Gy in 6 cases

40 - 50 Gy in 13

more than 50 Gy in 3 respectively. The periods between surgery and radiotherapy were 2 - 4 weeks in the combined treatment group. All patients were follow - up form 3 to 26 years. The 5 year survival rate was 95.2% (20/21) and the 10 year surivival rate was 87.5% (14/l6) respectively. Twenty of the 22 patients have been free of tumor until now (ranging from 3 to 26 years after treatment). They all live and work in the normal condition. There is no evidence of GCT malignization or secondary tumor occurrence in the irradiated lesions. Two patients died of GCT metastaaizing to the lungs 6 monthes and 7 years after radiotherapy. When surgical excision can’t be performed

or removal extent isn’t enough

or GCT relapse after operation

we recommend that sinle course of 45 - 55 Gy/5 - 6 weeks supervoltage