Study design: An experimental nonrandomized controlled study on tumor tissue samples. Objective: Estimation of the efficacy of thermablation using radiofrequency to treat metastases of the vertebrae. Summary of background data: Radiofrequency thermablation is one of the management techniques for vertebral metastatic lesions, which is developed and widely used in recent years. Materials: 12 metastatic lesions in 11 patients had undergone surgical intralesional excision and stabilization of the spine. During the surgery, tumor tissue samples were collected pre- and post-thremablation for analyses through histological and ultrastructural studies. However, presently there have been no reports on the evaluation of the tumor tissue necrosis, which should be one of the cogent proofs for the efficacy of this technique. Results: The total analyzed tissues under the light microscope showed 75% of necrosis, and went up to 83% necrosis under the electron microscope. This was mainly due to incomplete necrosis in the renal carcinoma metastases. Conclusions: Thermablation with radiofrequency treatments seems to effectively cause necrosis of the tumor tissues in nearly all the cases, as shown by the histological and ultrastructural studies.