A case of radiation myelopathy after radioactive iodine therapy is reported. This is the first report to describe radiation myelopathy after I-131 therapy. A 62-year-old female with spinal metastasis of T10 received I-131 therapy. She presented with radiation myelopathy 34 months after the irradiation. We need to recognize the possibility of this serious complication even in the case of I-131 therapy. There is a risk of radiation myelopathy even after I-131 therapy, especially in cases with spinal cord compression such as this.