We studied the effects of increased-dose radiation therapy in terms of survival time and improvement in the quality of life in 50 glioblastoma patients with minimal residual tumors. 1) Intraoperative radiotherapy ( IOR , 1,000-2,000 rad) was applied in 13 cases; the 2-year survival was 41.6%. However, in 9 patients who had undergone macroscopic total removal the 2-year survival rate was 68.6%. 2) Wide resection with necrotomy after conventional external irradiation was used in 9 cases and conformation irradiation was added; their 2-year survival was 44.4%. 3) In 22 patients who received only conventional irradiation following surgery, the 2-year survival was 7.5%.