To establish the role of ultrasound (US) in the assessment of cervical and abdominal lymph node metastases and its impact on making decision about surgical strategy in patients with squamous cell carcinoma of the thoracic esophagus. The results of US lymph node assessment before and after a neoadjuvant treatment in 83 patients were compared with the results of histopathological evaluation of lymph nodes harvested during surgery (transthoracic esophagectomy and 2-field extended or 3-field lymph node dissection). A diagnostic value of cervical and abdominal US in terms of sensitivity, specificity, positive and negative predictive value after a neoadjuvant treatment were determined. The sensitivity, specificity, positive and negative predictive value of the US assessment of cervical lymph node metastases were 100%, 96%, 81% and 100%, respectively. The sensitivity, specificity, positive and negative predictive value of the US assessment of abdominal lymph node metastases were 82%, 94%, 91.5% and 87%, respectively. The high sensitivity and specificity of cervical US make this investigational method sufficient in the assessment of cervical nodal involvement. In esophageal cancer patients with negative cervical lymph nodes on US, three-field lymph node dissection could be avoided. In patients with positive cervical lymph nodes on US one should consider to extend lymph node dissection about lymph nodes of the neck to achieve a curative resection. In patients with negative abdominal US this investigation should be supplemented by more detailed diagnostic methods.