Objective To study the function of radiosurgery on malignant glioma by analyzing prognostic factors affecting malignant gliomas treated with linac radiosurgery. Method Fifty-eight patients with deep situated malignant gliomas

aged 7 to 70 years

28 anaplastic astrocytomas and 30 glioblastomas multiforme were analyzed. The median volume of tumor was 10.67 cm3

and median prescription dose for linac radiosurgery was 20 Gy. Results were analyzed with Kaplan-Meier curve and Cox regression. Result In follow-up 44.8 percent tumors （26 patients） decreased in size. Median tumor local control interval was 10 months

15 months for anaplastic astrocytomas

and 9 months for glioblastoma multiforme. Tumor local control probability was 37.9 percent for 1 year and 10.3 percent for 2 years. Median survival was 22.5 months for anaplastic astrocytoma

13 months for glioblastoma multiforme

and 15 months for all patients. The survival probability was 79.3 percent at 1 year and 20.6 per-cent at 2 years. Isocenter numbers and tumor volume were the prognostic factors for tumor control

but conformity index was the prognostic factor for survival by Cox regression analysis. Considering pathology

only isocenter number and target volume significantly affected tumor control interval. Complications appeared in 44.8 percent patients and the median interval of com-plication onset was 8 months. Symptomatic cerebral edema was observed in 31.0 percent patients. Conclusion Linac radiosurgery can effectively improve tumor local control and prolong survival for deep situated mali-gnant gliomas.