[en] Purpose: To evaluate the efficacy of radiotherapy for the low-grade astrocytomas and confirm the variables influencing treatment results. Materials and methods: Forty-six patients with low-grade astrocytoma received radiotherapy after surgical removal (36 patients) or biopsy (10 patients) from 1979 to 1990. Twenty patients had grade I histology and 26 had grade II. External radiotherapy was done by conventional schedule with the total dose of 45 to 60 Gy (median; 54 Gy). The median follow-up period was 5 years. Results : The 2- and 5- year survival rates were 80% and 72%, respectively and the 2- and 5- year progression-free survival was 75% and 63%, respectively. The survival was influenced significantly by the histologic grade, the histologic type, and performance status. Major complication was not found. Conclusion : In spite of good survival, the local failure was still the major problem. Age and the extent of surgery as well as three favorable factors should be considered in the future treatments