목적: The aim of this study is to assess the effectiveness and safety of radiofrequent ablation (RFA) in debulking benign mostly solid thyroid nodules. 방법:Patients diagnosed with benign thyroid nodules were selected and treated with single session of RFA. This study included 102 patients with cytology result of Bethesda II FNA and followed up for 5 years between January 2018 to January 2023 at the Department of Head, Neck and Reconstructive Surgery of the National Cancer Center of Mongolia. 결과:All patients underwent a single treatment session. Most patients 112 (93%) were female and 9(7%) were male. The age ranged from 26 to 60 years old. Five follow-up examinations were conducted at 2 months, 6 months, 12 months, 2 years, and more than 2 years. Median nodule volume decreased from 6.2 9.7 mL at baseline to 1.23 5.59 after 60 months with a volume reduction ratio (VRR) of 50.3% 25.58%. Additionally, the size of the nodule was classified as small 3.11.34ml, medium 9.353.02ml, and large 22.658.43ml. After five follow up examination, the small nodules decreased from 3.11.34 to 0.662.93 (p value <0.01), the medium nodules decreased from 9.353.02 to 0.984.5 (p value <0.219) and the large nodules decreased from 22.658.43 to 5.756.96 (p value <0.54) respectively. All the nodules shrunk in size regardless of different dynamics during the observation period. According to the composition, the nodules were classified into cystic, spongiform, mixed and solid. In this study, RFA treatment was more effective for the solid nodules (p value <0.001). 결론:In conclusion, RFA is safe and effective minimally invasive treatment for benign thyroid nodules and its indication can include Bethesda III and IV as well considering the reported result of post RFA thyroidectomy by Italians and the Korean thyroid RFA guideline 2022. In our study, the smaller the size of thyroid nodules, the more effective the treatment of RFA. Nodules with solid composition tend to be more effectively reduced with RFA treatment.