Thyroid nodule is defined as "hot" on the bous it scintigraphic appearance. It can be defined like benign nodule with autonomous functionality. On scintiscan it shows high captation because there's an increase of production and secretion of thyroid hormones with total inhibition of TSH and suppression of extranodular tissue. Generally the treatment of hot thyroid nodule was surgical or with radio-metabolic therapy. Percutaneous ethanol injection (PEI) in the treatment of hot thyroid nodules has been suggested recently. The aim of our study was to value therapeutic effects of PEI under guidance by means of ultrasound in patients with hot nodules in toxic or pretoxic phase. 36 patients with autonomous thyroid nodules of 1.8-6 cm in diameter received sterile ethanol at 95% that has been injected with a 22-gauge needle and a probe with a guide device. The administrated dose varied from 1.2 to 1.5 ml for cc of tissue in 5-12 sessions. Ethanol injection was performed in a single site in nodules with diameter < 3 cm and in double sites in nodules with diameter > 3 cm. The patients were checked after treatment and then 3 and 6 months. Our experience confirms an excellent response to PEI in these patients. In fact after therapy symptoms of hyperthyroidism and hormonal levels become normal; no patient has even reached the range of subclinical or clinical hypothyroidism. Scintigram showed that previously suppressed thyroid tissue resumed functioning; at ultrasound all nodules had shrunk: thyroglobulin levels increased during treatment because ethanol induces coagulative intranodular necrosis with release in systemic circulation of this glycoprotein.(ABSTRACT TRUNCATED AT 250 WORDS)