The value of ultrasonography for detecting positive cervical lymph nodes in patients with intrathoracic esophageal carcinoma was studied. Positive cervical lymph nodes were detected by palpation in 26 of 209 patients. In 83 patients without palpable nodes, the sensitivity and the accuracy of ultrasonography for cervical lymph node metastases were 78.9% and 94.0%, respectively. Ultrasonography was useful for detecting positive cervical nodes in patients with intrathoracic esophageal carcinoma. For the 16 patients with positive cervical nodes detected by ultrasonography who underwent esophagectomy and neck lymph node dissection, the median survival was 26 months (range, 3 to 70 months), and the 3-year survival rate was 43.8%. There was a significant difference between the postoperative survival curves of the 12 patients with palpable cervical nodes and that of the 16 patients with positive cervical nodes detected by ultrasonography. In patients with intrathoracic esophageal carcinoma in whom palpation reveals no positive nodes, we believe that even if positive cervical nodes are revealed by ultrasonography, surgical intervention cannot be ruled out, and neck lymph node dissection is recommended for cure.