Abstract: Objective To analyze the effect of 131I-chTNT brachytherapy for deep-seated small glioma. Methods Twenty patients with deep-seated small glioma（＜4cm） who underwent stereotactic biopsy and Ommaya reservoir implantation in our department were enrolled in this study.They were given 131I-chTNT brachytherapy after operation,reexamined by MRI every month and followed up. Results 131I-chTNT brachytherapy was significantly effective for 4 patients,effective for 7 patients,ineffective for 4 patients,and deteriorated the disease in 10 patients,with a total effective rate of 44%.Different degrees of hypothyroidism were observed in patients 2 months after 131I-chTNT brachytherapy and their thyroid hormone level became stable after taking thyroxin tablets. Conclusion 131I-chTNT brachytherapy is effective for deep-seated small glioma.