Sonographically guided percutaneous ethanol injection (PEI) has been recently used with excellent results in the treatment of toxic and pretoxic thyroid adenoma. The aim of the present study was to assess the efficacy of PEI also in the treatment of "cold" thyroid nodules. Twenty patients, each with a single thyroid nodule, underwent PEI. In all cases the nodules were found to be cold by thyroid scintiscan. A total of 16.1 mL +/- 3.1 mL of ethanol was injected once a week. No adverse effects were observed during therapy. A striking nodular shrinkage was obtained in all cases, ranging from 72.8% to 97.6% (mean 84.5%, p < 0.001 vs pretreatment volume). These preliminary results suggest that PEI is an effective and safe therapy that may be useful in the treatment of thyroid nodules as an alternative to other therapies (surgery, L-thyroxine).