Objective — to determine the capabilities of ultrasonography (USG) for thyroid tumors metastasizing to the mediastinum. Subjects and methods. In 1992—2010, mediastinal USG was carried out in 151 patients with pathological thyroid changes, 87 of them were found to have mediastinal injury (22 men and 65 women; age 15 to 70 years). The investigators examined the thyroid and neck in accordance with the standard procedure, then an intrathoracic thyroid component and/or mediastinal lymph node (LN) metastases, by applying a special mediastinal USG procedure. Surgery was performed in 52 patients, including 22 and 30 patients who were found to have an intrathoracic thyroid tumor component and LN metastasis, respectively. Results. The ultrasound semiotics of an intrathoracic thyroid component and mediastinal lymph node metastases in thyroid cancer has been worked out. Conclusion. USG is an effective diagnostic technique for a thyroid tumor metastasizing to the mediastinum. Its sensitivity in diagnosing a thyroid tumor metastasizing to the mediastinum was 86.5%; its specificity and accuracy were 100% and 94%, respectively.