Changes suspicious for malignancy were detected in 127 patients who, according to scintigraphic examination of the thyroid, had "cold" nodules. As a consequence, all the patients were operated on and fine-needle aspiration findings were compared with the histological results. Thyroid cancer was identified in 18.9%. No differences in age between cases of benign, malignant follicular and Hurthle cell tumors were reported. Mean nodule size in patients with follicular and Hurthle cell adenoma (2.5 +/- 1.21 cm) differed from that in patients with thyroid cancer (3.35 +/- 1.86, p < 0.001). No differences in nodule size were observed in cases of micro-macrofollicular colloid goiter and thyroid cancer. The frequency of the latter was higher in Hurthle cell tumor (10 out of 23, 43.58%) than in thyroid tumor (14 out of 104, 13.56%), p = 0.002. Risk for thyroid cancer detection was higher in patients revealing nuclear atypia (10 out of 14 thyroid cancer patients, 71.4%) as compared with as low as 20 out of 79 adenoma patients, 25.32% (p = 0.03).