Objective:The purpose of this study was to examine the safety and clinical efficacy of CT-guided radioactive iodine-125 (125I) seed implantation treatment in patients with spinal metastatic tumors. Methods:We retrospectively analyzed 20 cases of spinal metastatic tumors, including 9 men and 11 women aged 50-79 years (mean age:61.1years). We used TPS to construct 3D images of the spinal metastatic tumors and to determinewhat number and dose rate distribution to use for the125I seeds. The matched peripheral dose (MPD) of the 125I seed implantation was 90-130Gy. Twenty-four spinal metastatic tumors were treated by CT-guided radioactive 125Iseed implantation. A median of 19 (range:4-43) 125I seeds were implanted. Results:Twenty cases were followed for a median of 15.3months (range: 7-32 months). The rate of pain relief was 95%. The median control time for all of the patients was 12.5 months. The 3-, 6-, and 12-month cumulative local control rates were 100, 95, and 60%, respectively. The median survival time for all of the patients was 16 months. The cumulative 6- and 12-month survival rates were 100 and 78.81%, respectively. No major complications were observed. No 125I seeds were lost or migrated to other tissues or organs. Conclusions:CT-guided radioactive 125Iseed implantation is a safe, effective, and minimally invasive method for the treatment of patients with spinal metastatic tumors. It is a possible alternative therapy for the treatment of spinal metastases.