OBJECTIVE To evaluate the therapeutic efficacy of treating glioblastoma with interstitial irradiation using radioactive seeds.METHODS First, the tumor was removed as completely as possible under an operating microscope. Then 125I seeds which had been selected were implanted in the tumor bed followed by routine radiotherapy after the operation. The time of progression (TTP) and overall survival (OS) of the patients were recorded, and statistically compared with patients who had received only surgery and radiotherapy for glioblastoma during the same period.RESULTS Nineteen patients, who were diagnosed with glioblastoma for the first time, with a mean age of 51.2 years, were involved in this study.Radioactive seeds (8～20) were implanted into the tumor bed after tumorectomy with a mean surrounding therapeutic dose of 31.6 Gy, followed by an external irradiation dose of 42～54 Gy. The average TTP in the group with implanted seeds was 42.1±2.4 w (95% confidence interval, 37.2～46.5 w), and 27.1±2.7 w (95% confidence interval, 24.3～31.8 w) in the control group. The average OS was 66.3±3.2 w (95% confidence interval, 61.9～70.4 w) and 47.7±2.6 w (95% confidence interval, 44.4～50.5 w), respectively. Statistical analysis showed there was a significant difference between two groups.CONCLUSION The survival time of patients with glioblastoma can be prolonged through radioactive seed implantation at the time of operation.This therapeutic method can rapidly reduce the tumor volume with a minimum number of seeds to avoid excessive radiation exposure. Because of some shortcomings of this study, such as a small number of patients, and because implantation was performed under the naked eye so that the seed alignment could not be verified accurately, the experience of combining implantation of seeds with external irradiation needs to be investigated further.