The aim of this study is to evaluate the therapeutic efficacy of computed tomography (CT)-guided interstitial iodine-125 (I) seed implantation for metastatic malignant melanoma treatment. From November 2008 to May 2011, 24 patients with metastatic malignant melanoma who had undergone surgery for excision of primary lesions and repeated chemotherapy underwent CT-guided I seed implantation. Their clinical situations, biochemical indicators, MRIs, and CTs were observed. The follow-up time ranged from 5 to 24 months (mean 19.6 months). The local control rates of metastatic malignant melanoma after surgery excision for primary lesion after 2, 6, 12, and 24 months were 86.8, 78.6, 62.1, and 55.0%, respectively. One patient died of liver failure 5 months after brachytherapy and another died of a metastatic brain tumor 8 months after brachytherapy. Two patients died of lung dysfunction from pulmonary metastases 15 months after brachytherapy. All other patients survived throughout the follow-up period. The 2-year survival rate was 83.3%. During the procedure, one patient presented with minimal bleeding from the applicator route and another presented with pneumothorax with 20% pulmonary compression, which improved after intraprocedure suctioning. Four patients had low-grade fever on day 3. Three showed mild decreases in their white blood cell counts. CT-guided I seed implantation is a safe, feasible, and promising approach to the treatment of patients with metastatic malignant melanoma after surgery excision for primary lesions and repeated chemotherapy, but large-scale randomized clinical trials should be conducted before the technique can be used routinely.