Ultrasound-guided percutaneous ethanol injection (PEI) was performed as a therapeutic procedure on twenty-four patients affected by toxic autonomously functioning thyroid nodules (AFTN). After treatment patients were followed up for a mean period of 12 months. PEI induced persistent and complete (clinical and hormonal) disease control in 19/23 cases (82.6%) that completed the procedure, normalization of serum FT4 and FT3 associated with a still suppressed TSH in 2/23 cases (8.6%) and failed to control hyperthyroidism in 2/23 cases (8.6%). After PEI all AFTN became smaller at clinical and US examination with a 60% mean volume decrease. Nodule shrinkage was related to cytological and histological findings of well circumscribed coagulative necrosis, granulomatous inflammation and progressive fibrosis. PEI induced two cases of temporary complications: 1 case of acute worsening of thyrotoxicosis and 1 case of self-resolving vocal cord paresis. No increase of serum autoantibodies (TgAb, TPOAb, TRAb) was detected during the follow-up period.