Abstract: Cervical and mediastinal lymph nodes ( CMLN) are usually close to some important ves-sels, nerves and organs, which brings much difficult for surgical and radiotherapy. CT-guided 125 I seed im-plantation is becoming an effective, safe and reliable treatment. CT could be used to observe the distribution of seeds, complication and therapeutic effect after the implantation. This paper focuses on the advances of CT-guided 125 I seed implantation on residual or relapsing metastatic CMLN.