Objective: To investigate the effects of ultrasound (US)-guided percutaneous laser ablation (PLA) in the treatment of benign solid hypoactive thyroid nodules on nodule volume, thyroid functions, nodule cytology and patients' complaints. Material and method: Criteria for enrollment in the study were as follows: patients with euthyroid. benign, hypofunctional nodule who had compressive symptoms or cosmetic complaints, but considered inoperable, or who rejected surgical treatment. PLA procedure at 3-5 watts (W) was applied to 15 thyroid nodules of 12 patients (4 male and 8 female; age range 20-78 yr, mean age 47.42±17.05 yr), and patients were followed up for 12 months. Thyroid functions and nodule volumes (ultrasonographically) were evaluated. US-guided fine needle aspiration biopsy (FNAB) was performed before and after the procedure, and biopsy specimens were cytologically evaluated. Results: The mean nodule volume before the procedure was 11.97 ml (min-max 0.95-26.30 ml). However, 12 months after the procedure the mean nodule volume was 2.21±2.32 ml (min-max 0.10-7.65 ml). The mean reduction in nodule volumes was 82%. Thyroglobulin levels reached peak values at 1 month after the procedure, and anti-thyroglobulin levels at 3 months after the procedure. FNAB performed at 12th month showed neutrophil polymorphs. macrophages, abundant cell debris, colloid, multinucleated giant cells, and small fragments of fibrous stroma which indicated that PLA procedure led to degenerative changes in nodules. Conclusion: US-guided PLA is a new, successful treatment method which is reliable in the long term in benign solid thyroid nodules for selected patients who are inoperable or do not prefer surgery. ©2006, Editrice Kurtis.