Objective To investigate the effectiveness and safety of ultrasound-guided percutaneous microwave ablation in the treatment of benign thyroid nodules. Methods A total 456 patients (912 nodules) underwent microwave ablation in our department. Microwave ablation was carried out using microwave antenna under local anesthesia. Nodule volume, thyroid function and clinical symptoms were evaluated before treatment and at 1, 3, 6 and 12 months after the treatment to monitor changes in the volume, adverse effect and complications. Results 912 nodules were all studied with contrast-enhanced ultrasound immediately after the ablation, and all results showed black hole sign. The mean follow-up period after microwave ablation was (9±6)months (range, 3-24 months). At 6-month follow-up, the mean volume reduction ratio of the solid nodules, mixed nodules and the cystic nodules was (61±50)%, (81±33)%, (89±46)%, respectively. The treatment was well tolerated and no major complications were observed except pain and transient voice changes (2.4%). Conclusions Microwave ablation is a safe and effective technique for the treatment of benign thyroid nodules. Key words: Ultrasonography; Microwave/therapeutic use; Thyroid nodule