Objective To preliminarily evaluate the feasibility and therapeutic effect of ¹²⁵I seed implantation under computed tomography (CT) guidance in the treatment of recurrent or metastatic chest wall tumor. Methods A retrospective analysis was performed on the clinical data of 23 patients with recurrent or metastatic malignant chest wall tumor who underwent ¹²⁵I seed implantation under CT guidance from July 2004 to October 2012. A computerized treatment planning system was used for three-dimensional treatment planning before operation to determine the number and spatial distribution of ¹²⁵I seeds. CT scan dosimetry was performed immediately after operation. The dose received by 90% of the target volume was 100—160 Gy (median:130 Gy). The activity of ¹²⁵I seeds was (1.85—2.89)×10⁷ Bq (median:2.63×10⁷ Bq). The total number of seeds implanted was 8—269(median:53). The local control rate and survival rate were calculated by the Kaplan-Meier method. Results The follow-up rate was 100%. Two patients were followed up for at least 3 years, and 2 for at least 5 years. Of the 23 patients, 4 had a complete remission, and 12 had a partial remission. The 1-, 3-, and 5-year local control rates were 82%, 62%, and 62%, respectively;the 1-, 3-, and 5-year tumor-specific survival rates were 61%, 45%, and 45%, respectively;the 1-, 3-, and 5-year overall survival rates were 58%, 58%, and 39%, respectively. After treatment, mild or moderate brachial plexus injury was seen in one patient, and grade 1 or 2 skin injury was seen in 6 patients. Conclusions ¹²⁵I seed implantation under CT guidance is safe and effective in the treatment of recurrent or metastatic chest wall tumor, according to the preliminary study