OBJECTIVE: The present study aimed to analyze the relationship between the incidence of complications and tumor size following thermal ablation of benign thyroid nodules (BTNs). METHODS: In this retrospective study, 1198 patients who underwent thermal ablation for unifocal BTN were enrolled. Receiver Operating Characteristic analysis was performed to select the cutoff values of the maximum diameter (MD) for dividing patients into different groups or subgroups. Multivariable logistic regression was performed to identify the risk factors. Propensity score matching (PSM) was employed to control for confounding variables. RESULTS: The overall complication rate was 3.8% (45/1198). Major complications included hoarseness (2.4%), nodule rupture (0.3%) and delayed hemorrhage (0.1%), whereas minor complications were limited to intraoperative hemorrhage (0.9%). The difference in the overall complication rate between the smaller group (<
3.15 cm) and the larger group (>
3.15 cm) was significant (1.0% vs. 6.5%, CONCLUSIONS: The incidence of complications in thermal ablation is greater for larger thyroid nodules, particularly for predominantly solid nodules with MDs greater than 3.15 cm.